Systems and procedures for engine diagnostics

Abstract

Method for a motor (110) which is operationally connected to a generator (120), comprising: Measuring at least one parameter associated with the generator (120) during operation; Determining a torque profile associated with the generator (120) based on at least one measured parameter; characterized by Retrieving the measured parameter over time and performing a frequency analysis of parameter data to determine a frequency content (420) of the torque profile; and Diagnosing the condition of the motor (110) based on the frequency content (420) of the determined torque profile.

Description

AREA

[0001] Embodiments of the subject matter disclosed herein relate to systems and methods for engine diagnostics. GENERAL STATE OF THE ART

[0002] Components of internal combustion engines or motors can deteriorate in various ways during operation. For example, an engine cylinder may lose its ignitability due to a worn spark plug. One method for detecting engine deterioration is by monitoring the engine speed. Examples of systems and methods known from the prior art are known, for example, from US Pat. No. 5,461,289 A, JP 2000-352 332 A, DE 10 2006 012 858 A1, and AT 009 466 U1.

[0003] Diagnostic routines allow monitoring whether engine speed components rise above a threshold and generating diagnostic codes or other indicators that require maintenance, a reduction in engine power, or engine shutdown. However, the inventors have recognized that analyzing engine speed is often inadequate for diagnosing an engine problem.

[0004] Based on the above-mentioned problem, the present invention is therefore based on the object of providing reliable methods and vehicle systems that are able to diagnose engine problems even more precisely.

[0005] The object is achieved by the features of independent patent claims 1, 4, 7, 10, 13 and 15. Advantageous developments of the invention are described in the subclaims. SHORT DESCRIPTION

[0006] In the embodiment according to claim 1, a method is provided for an internal combustion engine or motor operatively connected to a generator. The method includes measuring at least one parameter associated with the generator during operation, determining a torque profile associated with the generator based on the measured parameter, retrieving the measured parameter over time and performing a frequency analysis of parameter data to determine a frequency content of the torque profile, and diagnosing a condition of the engine based on a frequency content of the determined torque profile.

[0007] In one embodiment not part of the present invention, a method is provided for an internal combustion engine or motor operatively connected to a generator. The method includes measuring at least one parameter associated with the generator during operation, determining a torque profile associated with the generator based on the measured parameter, and distinguishing between different types of engine degradation based on a frequency content of the determined torque profile.

[0008] In the embodiment according to claim 4, a vehicle system is provided. The vehicle system includes an internal combustion engine or motor, a generator operatively connected to the engine, at least one sensor for measuring at least one parameter associated with the generator during operation, and a controller. The controller includes instructions configured to sample the measured parameter and convert it into a torque profile, identify a frequency content of the torque profile, retrieve the measured parameter over time, perform a frequency analysis of parameter data to determine the frequency content of the torque profile, and diagnose a condition of the engine based on the frequency content of the torque profile.

[0009] In one embodiment not forming part of the present invention, a test kit is provided. The test kit includes a controller configured to determine a condition of the engine based on the frequency content of a torque profile derived from measurements of parameters of a generator operatively connected to the engine.

[0010] In the embodiment according to claim 7, a method is provided for an internal combustion engine or motor operatively connected to a generator. The method includes measuring an electrical parameter associated with the generator during operation, retrieving the measured parameter over time and transforming it into a torque profile, performing a frequency analysis of parameter data to determine a frequency content of the torque profile, and diagnosing a condition of the motor based on a frequency content of the measured electrical parameter.

[0011] In the embodiment according to claim 10, a vehicle system is provided. The vehicle system includes an internal combustion engine or motor, a generator operatively connected to the engine, a sensor for measuring an electrical parameter associated with the generator during operation, and a controller. The controller includes instructions configured to sample the measured electrical parameter, identify a frequency content of the torque profile, retrieve the measured parameter over time and transform it into a torque profile, perform a frequency analysis of parameter data to determine the frequency content of the torque profile, and diagnose a condition of the engine based on the frequency content of the measured electrical parameter.

[0012] In one embodiment not forming part of the present invention, a test kit is provided. The test kit includes a controller configured to detect a condition of the engine based on a frequency content of an electrical parameter profile associated with a generator operatively connected to the engine.

[0013] In the embodiment according to claim 13, a method is provided for an internal combustion engine or motor operatively connected to a generator. The method includes measuring an electrical parameter associated with the generator during operation over time, determining a frequency content of the measured electrical parameter, and reconstructing a DC / DC modulation profile from at least a portion of the frequency content, wherein the DC / DC modulation profile is proportional to an electromagnetic torque of the generator.

[0014] In the embodiment according to claim 15, a method is provided for an internal combustion engine or motor operatively connected to a generator. The method includes measuring at least one parameter associated with the motor, measuring at least one parameter associated with the generator, and diagnosing a condition of the engine based on the measured parameters.

[0015] This brief description serves as a simplified introduction to a selection of designs described in more detail herein. This brief description is not intended to identify the most important features or essential features of the claimed subject matter, nor should it be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that partially or completely solve the problems stated in any part of the disclosure. BRIEF DESCRIPTION OF THE INVENTION

[0016] The invention will become apparent from reading the following description of non-limiting embodiments with reference to the accompanying drawings, in which: Fig. 1 is an illustration of an embodiment of a vehicle system (e.g., a locomotive system) having an engine and a generator (alternator), illustrated herein as a rail vehicle configured to travel on a rail via a plurality of wheels; Fig. 2 a representation of an embodiment of the motor and the generator of Fig. 1, which are operatively connected to various auxiliary devices 140 and electric drive motors; Fig. 3 is an illustration of embodiments of how frequency content is generated from a generator parameter retrieved as a function of time; Fig. Figure 4 is a diagram showing embodiments of “healthy” and “unhealthy” frequency content; Fig. 5 is an illustration of one embodiment of how diagnostic logic in the controller enables detection of an unhealthy condition in the frequency content of a generator parameter; Fig. 6 is an illustration of one embodiment of how a torque profile is generated from retrieved generator parameters; Fig. Figure 7 is an illustration of embodiments of how frequency content is generated from a time-domain torque profile; and Fig. Figure 8 is an illustration of an embodiment of how a DC / DC modulation profile is reconstructed from a frequency content of a measured electrical parameter of a generator. DETAILED DESCRIPTION

[0017] Embodiments of the subject matter disclosed herein relate to systems and methods for engine diagnostics. Test kits for performing the methods are also provided. The engine may be included in a vehicle, such as a locomotive system. Other suitable types of vehicles may include on-road vehicles, off-road vehicles, mining equipment, aircraft, and watercraft. Other embodiments of the invention may be used for stationary machines, such as wind turbines or power generators. The engine may be a diesel engine, or it may combust another fuel or combination of fuels. These alternative fuels may include, for example, gasoline, kerosene, biodiesel, natural gas, and ethanol, as well as combinations thereof. Suitable engines may have compression ignition or spark ignition.These vehicles may contain an engine with components that wear out due to use.

[0018] Furthermore, for embodiments of the subject matter disclosed herein, generator data may be used, for example, measured electrical generator parameters or generator data (e.g., a derived torque profile) derived from measured electrical generator parameters and / or engine parameters (e.g., speed) to diagnose conditions of an engine or accessory and to distinguish between conditions and associated engine components and accessory.

[0019] An engine can be placed into a specific operating condition or mode when looking for specific types of engine degradation. For example, the engine can be diagnosed under self-load conditions as part of a test procedure, under dynamic braking (db) conditions, or under steady-state monitoring conditions. The diagnostic and prognostic techniques discussed herein enable tracking trends, comparing cylinder-to-cylinder variations, performing test procedures, and confirming repair orders, facilitating repair. Alternatively, generator and / or motor data can be retrieved and analyzed when the engine is operating under specific conditions or in a specific state during normal operation.

[0020] Fig. 1 is an illustration of one embodiment of a vehicle system 100 (e.g., a locomotive system), depicted herein as a rail vehicle 106 configured to travel on a rail 102 via a plurality of wheels 108. As depicted, the rail vehicle 106 includes an engine 110 operatively connected to a generator (alternator) 120. The vehicle 106 also includes electric traction motors 130 operatively connected to the generator 120 to drive the wheels 108.

[0021] The vehicle 106 further includes various auxiliary systems or devices 140 that are operatively connected to the generator 120 or the engine 110 (e.g., the rotatable engine shaft 111, see Fig. 2) to perform various functions. The vehicle 106 further includes a controller 150 to control various components related to the vehicle system 100. In one example, the controller 150 includes a computer control system. In one embodiment, the computer control system is largely software-based and includes a processor, such as processor 152, configured to execute instructions that can be issued by a computer. The controller 150 may include multiple engine control units (ECUs), and the control system may be distributed among the individual ECUs. The controller 150 further includes computer-readable storage media, such as memory 154, containing instructions (e.g., computer-executable instructions) to enable on-board monitoring and control of the operation of the rail vehicle.Memory 154 may include volatile and non-volatile memory. According to another embodiment, the controller may be hardware-based and may use, for example, digital signal processors (DSPs) or other hardware logic circuits to perform the various functions described herein.

[0022] The controller may direct the control and monitoring of the vehicle system 100. The controller may receive a signal from an engine speed sensor 160 or from various generator sensors 170 to detect operating parameters and operating conditions and adjust various engine actuators 162 accordingly to control the operation of the rail vehicle 106. According to one embodiment, the speed sensor includes a multi-toothed pickup wheel connected to the motor shaft 111 and a reluctance sensor to detect when a tooth of the pickup wheel passes the reluctance sensor. For example, the controller may receive signals from various generator sensors representing various generator parameters. Examples of the generator parameters include a DC link voltage, a DC link current, a generator field voltage, a generator field current, a generator output voltage, and a generator output current.Other generator parameters are also possible according to various embodiments. Accordingly, the controller can control the vehicle system by sending commands to various components, such as drive motors, alternator, cylinder valves, throttle, etc. Signals from the generator sensors 170 can be bundled into one or more wiring harnesses to reduce the space occupied by wiring in the vehicle system 100 and to protect the signal wires from abrasion and vibration.

[0023] The control device may include electronic on-board diagnostics to record engine operating parameters. Operating parameters may include, for example, measurements from sensors 160 and 170. In one embodiment, the operating parameters may be stored in a database in memory 154. In one embodiment, current operating parameters may be compared with historical operating parameters to determine the trend in engine performance.

[0024] The controller may include electronic on-board diagnostics to identify and record potential degradations and failures of components in vehicle system 100. For example, if a potentially non-functional component is identified, a diagnostic code may be stored in memory 154. In one embodiment, each type of degradation identified by the controller may correspond to a unique diagnostic code. For example, a first diagnostic code may indicate a problem with cylinder 1 of the engine, a second diagnostic code may indicate a problem with cylinder 2 of the engine, a third diagnostic code may indicate a problem with one of the auxiliary systems, etc.

[0025] The controller may further be connected to a display 180, such as a diagnostic interface display, providing a user interface for the team operating the locomotive and a maintenance team. The controller may control the engine in response to operator input via user input controls 182 by sending a command to adjust various actuators 162 of the engine accordingly. Non-limiting examples of user input controls 182 may include a throttle control, a brake control, a keypad, and a power switch. Furthermore, operating characteristics of the engine and ancillary equipment, such as diagnostic codes corresponding to components no longer fully functional, may be reported to the operating and / or maintenance team via a display 180.

[0026] The vehicle system may include a communications system 190 connected to the controller. In one embodiment, the communications system 190 may include a radio and an antenna to send and receive voice and data messages. For example, data may be exchanged between the vehicle system and a railroad dispatch center, another locomotive, a satellite, and / or a trackside device such as a switch. For example, the controller may determine geographic coordinates of the vehicle system using signals from a GPS receiver. As another example, the controller may send operating characteristics of the engine and / or auxiliary equipment to the interlocking station via a message sent from the communications system 190.In one embodiment, a message may be sent from the communication system 190 to the interlocking station when a component of the engine or auxiliary device that is no longer fully functional has been detected, and maintenance may be scheduled for the vehicle system.

[0027] Fig. Figure 2 is an illustration of an embodiment of the motor 110 and the generator 120 of Fig. 1, which are operatively connected to various accessories 140 (141, 142, 143, 144) and drive motors 130. Various types of mechanical accessories 144 may be operatively coupled to and driven by the rotating motor shaft 111. Other accessories 140 are driven by the generator 120 via a rectifier 210, which generates a DC link voltage to power the controller 230. Examples of such accessories include a blower 141, a compressor 142, and a ventilation fan 143. The drive motors 130 are driven by the generator 120 via the rectifier 210, which generates a DC link voltage for an inverter 220. Such accessories 140, drive motors 130, and their practical implementations are known in the art.According to certain embodiments, generator 120 may actually consist of one or more generators, such as a main generator for driving drive motors 130 and an auxiliary generator for driving a portion of auxiliary equipment 140. Other examples of auxiliary equipment include, but are not limited to, chargers, pumps, and engine cooling systems.

[0028] The speed sensor 160 measures the speed of the rotating motor shaft 111 during operation. The DC link DC current / DC voltage sensor 171 is a generator sensor and is capable of measuring the DC link DC voltage, the DC link DC current, or both, according to various embodiments. The field sensor 172 is a generator sensor and is capable of measuring a generator field current, a generator field voltage, or both, according to various embodiments. According to certain embodiments, generator sensors 173 and 174 are provided to measure the current and voltage output by the generator armature, respectively. Suitable commercially available sensors can be selected based on application-specific parameters.

[0029] According to one embodiment, the frequency content of a generator parameter is used to diagnose a condition of the engine. Fig. 3 illustrates embodiments of how frequency content is generated from a time-retrieved generator parameter. A generator parameter (e.g., the DC link DC voltage) is measured using the DC link DC voltage sensor 171 and sent to the controller 150. Other generator parameters may be used instead, including the DC link DC current, the generator field voltage, the generator field current, the generator output voltage, and the generator output current. The controller 150 retrieves the generator parameter over time and performs frequency analysis processing on the generator parameter data. According to one embodiment, the frequency analysis processing is a Fourier transform method 310 (e.g., a Fast Fourier Transform, FFT method). According to another embodiment, the frequency analysis processing is a bandpass filter method 320.Frequency analysis processing transforms the retrieved time-domain generator parameter into frequency content in the frequency domain. Examples of the various frequency components of the frequency content include fundamental frequency components (first-order components) and harmonic frequency components (second-order, half-order, third-order, etc. components). According to one embodiment, the Fourier transform method and the bandpass filter method involve computer-executable instructions executed by processor 152. Frequency transformation can be performed on processed / derived signals, such as kilovolt-amps (kVA) or kilowatts (kW), which are the product of current and voltage, or torque, which is the kW / frequency of the signal.

[0030] For example, the engine may have a plurality of cylinders that fire in a predetermined sequence, with each cylinder firing exactly once during a four-stroke or two-stroke cycle. For example, a four-cylinder / four-stroke engine may have a firing order of 1-3-4-2, where each cylinder fires exactly once every two engine revolutions. Thus, the firing frequency of a particular cylinder is half the engine revolution frequency, and the firing frequency of all cylinders is twice the engine revolution frequency. The engine revolution frequency can be described as the first engine order. Such a first-order frequency component can be reflected in the frequency content of the measured generator parameter. The firing frequency of a particular cylinder of a four-stroke engine can be described as half the engine order, where half the engine order is half the engine revolution frequency.Such a half-order frequency component can be seen in the frequency content of the measured generator parameter.

[0031] As another example for a four-stroke engine, a twelve-cylinder engine may have a firing order of 1-7-5-11-3-9-6-12-2-8-4-10, where each cylinder fires exactly once per two engine revolutions. Thus, the firing frequency of a given cylinder is half the engine revolution frequency, and the firing frequency of all cylinders is six times the engine revolution frequency. As another example for a two-stroke engine, a twelve-cylinder engine may have a firing order of 1-7-5-11-3-9-6-12-2-8-4-10, where each cylinder fires exactly once per engine revolution. Thus, the firing frequency of a given cylinder is the engine revolution frequency, and the firing frequency of all cylinders is twelve times the engine revolution frequency. Again, these frequency components may be reflected in the frequency content of the measured generator parameter.

[0032] For example, the engine may be a four-stroke engine operating at 1050 rpm. Thus, the first motor order is 17.5 Hz, and half the motor order is 8.75 Hz. The intermediate circuit DC voltage may vary at a periodic frequency as the motor shaft 111 rotates during operation. For example, the frequency content of the intermediate circuit DC voltage may be a frequency component with the frequency of the first motor order. In other words, the upper peak value of the frequency content may occur at the first-order frequency component. The intermediate circuit DC voltage may also contain frequency content at other harmonics of the first-order frequency, for example, a second-order frequency (twice the motor frequency), a third-order frequency (three times the motor frequency), etc.Likewise, the intermediate circuit DC voltage may contain a frequency content at frequencies lower than the first-order frequency, for example at a half-order frequency (half the motor frequency).

[0033] For a motor that is "healthy" and operating properly, the frequency content of the measured generator parameter is capable of exhibiting a very specific healthy signature. Deviations from this healthy signature are capable of indicating a problem with the motor. For example, according to one embodiment, a motor condition can be diagnosed by analyzing a half-order magnitude and / or phase of the frequency content.

[0034] Fig. Figure 4 is a diagram illustrating embodiments of "healthy" and "unhealthy" frequency content. The frequency content 410 of the healthy motor (i.e., a motor operating properly) has, according to one embodiment, three frequency components with absolute and relative magnitudes, as shown in Fig. 4. The frequency content 420 of the unhealthy motor (i.e., a motor that is not operating properly due to degradation or failure) has three frequency components at the same locations as the frequency content 410 of the healthy motor. However, according to one embodiment, the amplitude of one frequency component 421 (e.g., a half-order component) is distorted (e.g., the amplitude is increased), and the amplitude of another frequency component 423 (e.g., a second-order component) is also distorted (e.g., the amplitude is decreased). In one embodiment, the distorted half-order component 421 is indicative of an unhealthy motor and is identified by comparing the amplitude of the half-order component to a threshold.

[0035] According to another embodiment, both distorted frequency components 421 and 423 in frequency content 420 indicate an unhealthy engine. Furthermore, the specific characteristics of the distorted frequency components (e.g., amplitude) relative to the other frequency components in frequency content 420 of the unhealthy engine are capable of indicating a specific type of engine degradation or failure (e.g., the engine's number 3 cylinder is no longer operating). Likewise, using the phase of the half-order component relative to a reference cylinder (e.g., cylinder number 1) allows for the isolation of a problem to a specific cylinder.

[0036] For example, components that are no longer fully functional can cause the engine to operate less efficiently, produce less power, and / or emit more pollutants. Furthermore, the condition of the components that are no longer fully functional can accelerate the deterioration of the components, which can increase the likelihood of catastrophic engine failure and track retirement. A deteriorating engine cylinder is an example of a deteriorating engine component. For example, in a four-stroke engine, the distorted frequency component may occur at half-order frequency. In a two-stroke engine, the distorted frequency component may occur at first-order frequency. The diagnosis can then include both a warning indication of the deterioration in function and an indication of the type and / or location of the engine component that is no longer fully functional.

[0037] Fig. 5 is an illustration of one embodiment of how diagnostic logic 510 in controller 150 may detect an unhealthy condition in the frequency content of a generator parameter. For example, diagnostic logic 510 may compare the half-order component 421 to a threshold T. If the magnitude of component 421 exceeds threshold T, diagnostic logic 510 determines that the engine is no longer fully functional. If diagnostic logic 510 further determines that the ratio of the half-order component 421 to the first-order component 422 exceeds a second threshold and the ratio of the first-order component 422 to the second-order component 423 exceeds a third threshold, diagnostic logic 510 isolates the degradation to a specific engine component (e.g., cylinder number 3).According to one embodiment, the diagnostic logic includes computer-executable instructions executed by processor 152. According to one embodiment, the ratio of a half-order component to a DC current or voltage component or a zero-order component is capable of indicating a motor problem. Furthermore, the threshold T may depend on an operating condition of the motor, such as power, speed, environmental conditions, repair history, etc.

[0038] Types of engine malfunctions or failures that can be diagnosed, differentiated, and isolated include a worn spark plug, fuel imbalance, a faulty cylinder, engine knocking, low fuel flow, low compression, and valve train failure. Diagnosing a malfunction or failure allows for immediate action. Such action may include, for example, issuing a warning signal to the operator (e.g., via display 180), adjusting an engine operating parameter (e.g., reducing engine power, shutting down at least one engine cylinder, shutting down the entire engine, balancing the engine cylinders), scheduling a maintenance action, and sending the diagnosed condition to a central location (e.g., via communication system 190).

[0039] According to one embodiment, the frequency content of a torque profile associated with the generator is used to diagnose a condition of the engine. Fig. 6 is an illustration of embodiments of how a torque profile is generated from retrieved generator parameters. Controller 150 includes a backward model 610 of diode rectifier 210 and a model 620 of generator 120. The intermediate circuit DC voltage, measured by intermediate circuit DC voltage sensor 171, is input to backward model 610 to generate an estimate of the generator's armature (or stator) voltage (i.e., generator output voltage). Likewise, generator field current, measured by field sensor 172, is input to generator model 620 to generate an estimate of the generator's armature (or stator) current (i.e., generator output current). Controller 150 further includes a torque determination model 630.The determined generator output voltage and current are input to the torque determination model along with a motor speed input, and a generator torque profile is generated (e.g., an electromagnetic torque profile). A motor speed input is used to tell the torque determination model 630 where the harmonic frequencies of interest are located. The motor speed from the speed sensor 160 can be used as an input, or the frequency content (e.g., the sixth harmonic) from the rectifier 210 (e.g., the frequency content of the intermediate circuit DC voltage signal) can be used as a motor speed input.

[0040] As a result, a torque profile associated with the generator can be derived from the DC link DC voltage and the generator field current. Alternatively, the DC link DC current and the generator field voltage could be used with appropriate models to determine the generator output current from the DC link DC current and the generator output voltage from the generator field voltage. If the generator output voltage and the generator output current have already been provided to the controller 150 (since these sensors are located on the generator), the backward model 610 and the generator model 620 can be bypassed.If a less accurate determination of the torque profile is acceptable, it is possible to use only one of the parameters (DC link DC voltage, DC link DC current, generator field current, generator field voltage, generator output current, generator output voltage) instead of two to determine a torque profile.

[0041] It is possible to diagnose a motor condition based on the frequency content of the torque profile. Fig. 7 is an illustration of embodiments of how frequency content is generated from the time-domain torque profile. Again, it is possible to use a Fourier transform method 310 or a bandpass filter method 320 of controller 150 to generate the frequency content. Likewise, as discussed above, it is possible to analyze the frequency content using the diagnostic logic of controller 150 to determine engine degradation. It is possible to compare various aspects (e.g., amplitude and phase) of the frequency components (e.g., half-order, first-order, etc.) and / or their ratios to thresholds to determine engine component degradation.

[0042] According to one embodiment, it is possible to reconstruct a DC / DC voltage modulation profile from at least part of the frequency content of generator measurement data (e.g., data on the intermediate circuit DC voltage). As described in Fig. As shown in Figure 8, a Fourier transform method 810 (e.g., an IFFT method) of controller 150 is used to reconstruct the DC / DC modulation profile from the frequency content. The DC / DC modulation profile is proportional to an electromagnetic torque of the generator. The reconstructed DC / DC modulation profile can be analyzed to diagnose a condition of the motor.

[0043] In general, according to various embodiments, it is possible to diagnose a motor condition based on a combination of measured parameters from the motor (e.g., speed or pressure) and the generator (e.g., intermediate circuit DC voltage, etc.). It is possible to determine and compare the frequency content of the various parameters to diagnose a specific motor condition. Furthermore, it is also possible to determine other parameter profiles (e.g., torque) from the measured parameter profiles and subsequently analyze the frequency content of these profiles to diagnose a specific motor condition.

[0044] Further examples of applications of the systems and methods described herein are now provided. The examples illustrate various methods for diagnosing and distinguishing various types of motor degradation based on the frequency content of generator data (e.g., a relatively unprocessed generator parameter such as the intermediate circuit DC voltage or other derived generator parameters such as electromagnetic torque) associated with the generator, or a motor speed during motor operation. Many of the examples can also be applied to various types of auxiliary equipment with minor adaptations.

[0045] In one embodiment, a non-functional cylinder of a four-stroke engine may be identified based on a frequency content signature, for example, the magnitude of the half-order frequency component being greater than a half-order threshold. In an alternative embodiment, the magnitudes of the frequency contents may be integrated over a range of frequencies, and a non-functional cylinder of a four-stroke engine may be identified based on the integration being greater than an integral threshold.

[0046] Detecting a single inoperative cylinder when the other engine cylinders are healthier (or less severely impaired) may have a more distinct frequency content signature than when multiple engine cylinders are inoperative. For example, the frequency content signature of a single inoperative cylinder can be identified by comparing the magnitude of the half-order frequency component to a threshold half-order magnitude. However, multiple inoperative cylinders may have a different frequency content signature than a single inoperative cylinder. Furthermore, the firing order position of multiple inoperative cylinders can change the frequency content signature.For example, two non-functional cylinders that are 180° out of phase may have a different frequency content signature than two non-functional cylinders that follow one another in the firing order. Thus, the methods disclosed herein may identify one or more non-functional cylinders based on various changes in the frequency content signature. Furthermore, it may be advantageous to generate a healthy engine frequency content signature by recording frequency content at different frequencies and under different operating conditions. In one embodiment, the engine's frequency content may be compared to the healthy engine frequency content signature.For example, anomalies that do not match the frequency content signature of the healthy engine or another malfunctioning engine component can be identified and reported by the control device. Other examples of malfunctioning engine components include a malfunctioning crankcase ventilation system, a malfunctioning supercharger, and a malfunctioning crankcase.

[0047] In one embodiment, the time-domain generator data may be filtered through a low-pass filter with a cutoff frequency slightly greater than the first-order frequency. For example, the cutoff frequency may be ten to twenty percent greater than the first-order frequency. Thus, in one embodiment, the cutoff frequency may be determined by the engine speed. The generator data may be sampled over time at a frequency at least as high as the Nyquist rate. In one embodiment, the time-domain signal may be sampled at a frequency greater than twice the first-order engine frequency. In one embodiment, the time-domain signal may be sampled at a frequency greater than twice the engine frequency at which a red line is crossed.Thus, it is possible that low-pass filtering and sampling at a frequency at least as high as the Nyquist rate will not corrupt the frequency content of the generator data. The same can apply to engine speed data.

[0048] As discussed herein, the sampled generator data (e.g., DC link voltage, torque, etc.) may be transformed to generate frequency-domain frequency content. In one embodiment, a Fast Fourier Transform may be used to generate the frequency-domain frequency content. In one embodiment, a correlation algorithm may be applied to compare the frequency content of the generator data to a signature for a condition of the engine. For example, the signature for a healthy engine may have frequency content with a magnitude below a first-order threshold at the first-order frequency and frequency content with a magnitude below a half-order threshold at the half-order frequency. The first-order threshold may correspond to engine speed, engine load, crankcase temperature, and engine history data.

[0049] For example, the engine and generator history data can be stored in a database containing samples of frequency content from past engine operation. Thus, a trend in the frequency content can be identified, and the trend can be used to determine the health of the engine. For example, an increase in the magnitude of the engine's half-order component for a given engine speed and load may indicate that a cylinder is no longer fully functional. As another example, an increasing average crankcase pressure coupled with no increase in the magnitude of the engine's half-order component for a given engine speed and load may indicate that the supercharger or crankcase ventilation system is losing functionality.A potential failure may include a cylinder that is no longer fully functional, a charger that is no longer fully functional, or a crankcase ventilation system that is no longer fully functional.

[0050] In one embodiment, the frequency content of the generator data may be stored in a database containing historical engine and generator data. For example, the database may be stored in memory 154 of controller 150. As another example, the database may be stored at a location other than on rail vehicle 106. For example, historical data may be encapsulated in a message and sent using a communications system 190. In this way, a control center may monitor the health of the engine in real time. For example, the control center may perform steps to diagnose the condition of the engine using generator data sent using communications system 190.For example, the interlocking system can receive generator data, including DC link voltage data, from rail vehicle 106, transform the DC link voltage data to frequency, apply a correlation algorithm to the transformed data, and diagnose potential engine degradation. Furthermore, the interlocking system can schedule maintenance and deploy serviceable locomotives and maintenance crews in a manner that optimizes capital expenditure. Historical generator data can also be used to evaluate engine health before and after engine service, engine modifications, and engine component replacement.

[0051] In one embodiment, a potential fault may be reported to the locomotive operating team via display 180. Upon notification, the operator may adjust the operation of the rail vehicle 106 to reduce the likelihood of further engine degradation. In one embodiment, a message indicating a potential fault may be sent to a signaling center using communication system 190. Furthermore, the severity of the potential fault may be reported. For example, diagnosing a fault based on the frequency content of generator data may enable earlier fault detection than if the fault is diagnosed using only average engine information (e.g., only speed information). Thus, if a potential fault is diagnosed in the early stages of engine degradation, the engine may continue to operate.In contrast, if a potential fault is diagnosed as severe, it may be desirable to stop the engine or schedule immediate maintenance. In one embodiment, the severity of a potential fault may be determined according to a difference between a threshold and the magnitude of one or more components of the frequency content of the generator data.

[0052] By analyzing the frequency content of the generator data, it may be possible to monitor and diagnose the engine during operation. Furthermore, the operation of an engine with a component that is no longer fully functional may be adjusted to potentially mitigate further functional degradation of the engine component and to reduce the likelihood of additional engine failure and in-service failure. For example, the half-order component may be compared to a half-order threshold. If the magnitude of the half-order component is greater than the half-order threshold, the potential fault, in one embodiment, may be a cylinder that is no longer fully functional.However, if the half-order component size is not larger than the half-order threshold, the potential failure may be a malfunctioning charger or a malfunctioning crankcase ventilation system.

[0053] In one embodiment, the potential fault may be reported to the locomotive operator team via display 180, and the operator may adjust the operation of the rail vehicle 106 to reduce the risk of further deterioration. In one embodiment, a message diagnosing the potential fault may be sent to an interlocking station using communication system 190.

[0054] In one embodiment, an engine operating parameter may be adjusted to identify a cylinder that is no longer fully functional. For example, the cylinder that is no longer fully functional may be identified based on selectively disabling fuel injection to one or more cylinders of the engine. In one embodiment, fuel injection may be disabled for each of the plurality of cylinders in turn while monitoring generator data and / or associated frequency content. For example, fuel injection may be disabled to one cylinder while the other cylinders are operating normally. By disabling each cylinder in turn, the cylinder that is no longer fully functional may be identified.As another example, fuel injection can be disabled in a group of cylinders while the other cylinders operate normally. By cycling through different groups in sequence, the cylinder that is no longer fully functional can be identified through a process of elimination.

[0055] In one example, the half-order frequency component of the generator data may be monitored for each disabled cylinder of a four-stroke engine. The disabled cylinder may be a de-energized cylinder if the half-order frequency component falls below a half-order threshold while the cylinder is disabled. The disabled cylinder may be a de-energized cylinder if the half-order frequency component remains above a half-order threshold while the cylinder is disabled. In other words, the de-energized cylinder may be the cylinder that contributes more to the frequency content at the half-order frequency component than other cylinders. In one embodiment, the diagnostics provided by selective de-energization may be performed when the engine is idling or only lightly loaded.

[0056] In one embodiment, the diagnosis provided by selective override may further be based on the frequency content of engine operating parameters, such as engine speed. For example, engine speed may include frequency content at the half-order frequency component when a no longer fully functional cylinder is operating. Thus, by observing the frequency content of various engine operating parameters while selectively overriding each cylinder, the no longer fully functional cylinder may be identified.

[0057] In one embodiment, the inoperative cylinder may be identified based on a selective change in fuel injection to one or more cylinders of the engine. For example, fuel may be selectively increased or decreased for individual cylinders while monitoring the half-order frequency component of the generator data. Further, the signature, i.e., the frequency content, of each cylinder may be compared to historical data for the engine or to a healthy engine. For example, the diagnostic test may be performed on a healthy engine to generate a baseline signature. The baseline signature may then be compared to the frequency content while the engine is undergoing diagnostics. In one embodiment, the inoperative cylinder may be identified by changing the fuel injection timing.For example, advance angle adjustments can be used to diagnose a cylinder that is no longer fully functional. For example, fuel injection timing can be delayed to potentially increase the frequency content of the half-order frequency component.

[0058] It may be more preferable to shut down the engine than to allow a non-functional cylinder to fail in a manner that could cause further damage to the engine. In one embodiment, a threshold may be determined indicating that continued operation of the engine may be detrimental because the potential failure is severe. For example, the potential failure may be classified as severe if a magnitude of the half-order frequency component exceeds a threshold. The engine may be stopped if the severity of the potential failure exceeds the threshold.

[0059] A request to schedule a workshop inspection may be sent, for example, through a message sent via the communication system 190. Furthermore, by sending the potential fault condition and the severity of the potential fault, the time that the rail vehicle 106 is out of service may be reduced. For example, maintenance work on the rail vehicle 106 may be postponed to a later time if the potential fault is not very severe. The downtime may be further reduced by derating the engine power, for example, by adjusting an engine operating parameter based on the diagnosed condition. It may be determined whether engine derating is permissible. For example, derating the engine power may reduce the magnitude of one or more components of the frequency content of the generator data.

[0060] An engine operating parameter may be adjusted, for example, to mitigate further functional degradation of the component that is no longer fully functional. In one embodiment, the engine speed or power may be regulated.

[0061] In one embodiment, fuel injection to the potentially inoperative cylinder may be reduced or disabled while the operation of the other cylinders continues. Thus, the engine can continue operating, and further degradation of the inoperative cylinder may be reduced. In this way, the engine may be adjusted to potentially reduce additional engine component degradation and reduce the likelihood of catastrophic engine failure and track failure. In one embodiment, a test kit may be used to detect a frequency content of the generator data and diagnose a condition of the engine based on the frequency content of the generator data associated with the generator.For example, a test kit may include a controller configured to communicate with one or more generator sensors and retrieve the associated generator data. The controller may further be configured to transform signals from the one or more generator sensors into frequency content representing frequency information of the engine. The controller may further be configured to diagnose a condition of the engine based on the frequency content of the generator data from the generator sensor. The test kit may further include one or more sensors for sensing generator parameters (e.g., generator output voltage) and / or engine parameters (e.g., engine speed).

[0062] Throughout the description and claims, reference is made to a number of terms having the following meanings. The singular forms "a," "an," and "the" include plural referents unless the context indicates otherwise. Approximate terms, as used throughout the description and claims, may be applied to modify a quantitative statement that could vary in a permissible way without resulting in a change in the basic function to which it is related. Thus, a value modified by a term such as "about" is not intended to be limited to the exact value stated. In some cases, the approximate terms may correspond to the accuracy of an instrument used to measure the value.Accordingly, "free" can be used in combination with a term and can include a negligible number or trace amount and still be considered free from the modified term. Furthermore, the use of the terms "first," "second," "second," etc., does not indicate any order or significance unless specifically stated otherwise. Rather, the terms "first," "second," "second," etc., are used to distinguish one element from another.

[0063] As used herein, the terms "may" and "can be" indicate a possibility for occurrence within a set of circumstances; the possession of a particular property, characteristic, or function; and / or it qualifies another verb by expressing a capability, ability, or possibility associated with the verb. Accordingly, the use of "may" and "can be" indicates that a modified term is obviously appropriate, fitting, or suitable for a stated capability, function, or use, while recognizing that under some circumstances the modified term may not be appropriate, capable, or suitable.For example, an event or capability may be expected under some circumstances, while the event or capability may not occur under other circumstances—the distinction is made by the terms "may" and "may be." The terms "generator" and "alternator" are used interchangeably herein (although it should be understood that depending on the application, one or the other term may be more appropriate). The terms "frequency content" and "harmonic content" are used interchangeably herein and may refer to fundamental frequency (and / or phase) components and associated harmonic frequency (and / or phase) components above and below the fundamental component. The term "instructions," as used herein with reference to a controller or processor, may refer to computer-executable instructions.As used herein, the terms “speed,” “speed data,” and “speed signal” may refer to a speed at which a motor rotates, a harmonic content of a measured motor speed, a cycle-to-cycle difference in a measured motor speed, a difference in the time it takes a motor to rotate through a specified angle, and a plurality of time intervals, each time interval corresponding to the length of time it takes a motor to rotate through a specified angle.

[0064] The embodiments described herein are examples of articles, systems, and methods that include elements corresponding to the elements of the invention recited in the claims. The description may enable one skilled in the art to make and use embodiments having alternative elements that also correspond to the elements of the invention recited in the claims. Thus, the scope of the invention includes articles, systems, and methods that do not differ from the literal language of the claims and further includes other articles, systems, and methods that differ only insubstantially from the literal language of the claims. Although only certain features and embodiments are shown and described herein, many modifications and changes may be obvious to one skilled in the art. The appended claims cover all such modifications and changes.

Claims

[1] A method for an engine (110) operatively connected to a generator (120), comprising: Measuring at least one parameter associated with the generator (120) during operation; Determining a torque profile associated with the generator (120) based on the at least one measured parameter; characterized by Retrieving the measured parameter over time and performing a frequency analysis of parameter data to determine a frequency content (420) of the torque profile; and Diagnosing a condition of the motor (110) based on the frequency content (420) of the determined torque profile. [2] The method of claim 1, wherein the at least one measured parameter includes at least one of the following quantities: intermediate circuit (171) DC voltage, intermediate circuit (171) DC current, field current in the generator (120), field voltage in the generator (120). [3] The method of claim 1, wherein in response to the diagnosis it includes at least one of the following actions: issuing a warning signal to an operator, reducing the power of the engine (110), sending the diagnosed condition to a central location, shutting down at least one cylinder of the engine (110), shutting down the engine (110), balancing the cylinders of the engine (110). [4] Vehicle system (100), comprising: an engine (110); a generator (120) operatively connected to the engine (110); at least one sensor (170) for measuring at least one parameter associated with the generator (120) during operation; and a controller (150) containing instructions configured to retrieve the at least one measured parameter and transform it into a torque profile; to detect the frequency content (420) of the torque profile; characterized by Retrieving the measured parameter over time and performing a frequency analysis of parameter data to determine the frequency content (420) of the torque profile; and to diagnose a condition of the motor (110) based on the frequency content (420) of the torque profile. [5] The vehicle system (100) of claim 4, wherein the control device (150) is operable to report a functionally degraded condition of the engine (110). [6] The vehicle system (100) of claim 4, wherein the controller (150) further includes instructions configured to adjust an operating parameter of the engine (110) based on the diagnosed condition. [7] A method for a motor (110) operatively connected to a generator (120), comprising: Measuring an electrical parameter associated with the generator (120) during operation; characterized by Retrieving the measured parameter over time and transforming it into a torque profile; and Performing a frequency analysis of parameter data to determine a frequency content (420) of the torque profile; and Diagnosing a condition of the motor (110) based on the frequency content (420) of the measured electrical parameter. [8] The method of claim 7, wherein the condition is diagnosed by analyzing a magnitude and / or a phase of a half-order frequency component of the frequency content. [9] The method according to claim 7, wherein the electrical parameter is a DC voltage of an intermediate circuit (171), an intermediate circuit (171) DC current, a field voltage of the generator (120), a field current of the generator (120), an output voltage of the generator (120) or an output current of a generator (120). [10] Vehicle system (100), comprising: an engine (110); a generator (120) operatively connected to the engine (110); a sensor (170) for measuring an electrical parameter associated with the generator (120) during operation; and a control device (150) containing instructions configured to sample the measured electrical parameter; to identify the frequency content (420) of the measured electrical parameter; characterized by Retrieving the measured parameter over time and transforming it into a torque profile; and Performing a frequency analysis of parameter data to determine the frequency content (420) of the torque profile; and to diagnose a condition of the motor (110) based on the frequency content (420) of the measured electrical parameter. [11] The vehicle system (100) of claim 10, wherein the electrical parameter is an intermediate circuit (171) DC voltage, an intermediate circuit (171) DC current, a field voltage of the generator (120), a field current of the generator (120), a generator (120) output voltage, or a generator (120) output current. [12] The vehicle system (100) of claim 10, wherein the controller (150) diagnoses a condition by analyzing a magnitude and / or a phase of a half-order frequency component (421) of the frequency content (420). [13] A method for a motor (110) operatively connected to a generator (120), comprising: Measuring an electrical parameter associated with the generator (120) during operation over time; Determining a frequency content (420) of the measured electrical parameter; and Reconstructing a DC / DC modulation profile of at least a portion of the frequency content (420), wherein the DC / DC modulation profile is proportional to an electromagnetic torque of the generator (120). [14] The method of claim 13, further comprising diagnosing a condition of the motor (110) based on the reconstructed DC / DC voltage modulation profile. [15] A method for a motor (110) operatively connected to a generator (120), comprising: Measuring at least one parameter associated with the engine (110); Measuring at least one parameter associated with the generator (120); and Diagnosing a condition of the engine (110) based on the measured parameters.

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