Systems and procedures for diagnosing an engine

Abstract

Method for a reciprocating piston engine (110), comprising the steps: Diagnosing a condition of the engine (110), characterized by the fact that The diagnosis is based on: a time difference for the reciprocating engine (110) to rotate over a predetermined angle from cycle to cycle.

Description

AREA

[0001] Embodiments of the invention described herein relate to systems and methods for diagnosing an engine.

[0002] Embodiments known from the prior art can be found, for example, in US 2003 / 0 089 338 A1, US 6 021 758 A, DE 10 2008 050 287 A1, DE 10 2008 032 174 A1 or US 2005 / 0 229 904 A1.

[0003] Engine components can deteriorate in various ways during operation. For example, a cylinder in an engine might begin misfiring due to a worn spark plug. One way to detect engine deterioration is by monitoring engine speed. Diagnostic routines can monitor whether engine speed components exceed a threshold and generate diagnostic codes or other indications that require service, reduced engine power, or engine shutdown. However, the inventors of this method recognized that a conventional analysis of engine speed is often insufficient for a thorough diagnosis of an engine problem.

[0004] Based on this disadvantage, the present invention therefore aims to provide a reliable solution for accurately diagnosing an engine problem.

[0005] The aforementioned problem is solved according to the invention by the features of the independent claims. Advantageous embodiments of the invention are described in the dependent claims. SHORT DESCRIPTION

[0006] According to one embodiment of the invention, a method for a reciprocating engine is described. The method according to the invention includes diagnosing an engine condition based on time differences for the reciprocating engine to rotate through a predetermined angle.

[0007] In one embodiment of the invention, a method is described for a reciprocating engine functionally connected to a generator. The method includes measuring the rotational speed of the reciprocating engine over time, measuring electrical parameters associated with the generator over time, correlating the characteristics of the measured rotational speed with the characteristics of the measured electrical parameters, and diagnosing the engine condition based on the correlated characteristics.

[0008] In a further embodiment of the invention, a method for a reciprocating piston engine is described. The method includes measuring the rotational speed of the reciprocating piston engine over time, determining a torque profile by combining acceleration components derived from the measured rotational speed at determined characteristic frequencies, and diagnosing the engine condition based on the properties of the torque profile.

[0009] In one embodiment of the invention, a vehicle system is disclosed. The vehicle system includes a reciprocating engine, a sensor for measuring the rotational speed of the reciprocating engine over time, and a control device with instructions configured to sample the measured rotational speed and determine an engine state based on differences in the time it takes the engine to rotate through a predetermined angle.

[0010] In a further embodiment of the invention, a vehicle system is described. The vehicle system includes a motor, a generator functionally connected to the motor, a sensor for measuring the motor speed over time, sensors for measuring electrical parameters associated with the generator during operation, and a control device with instructions configured for scanning the measured speed and electrical parameters and for diagnosing a motor condition based on correlations between the measured speed characteristics and the electrical parameters of the generator.

[0011] In a non-inventive embodiment, a test set is described. The test set includes a control device that can be operated to determine the state of a reciprocating piston engine based on at least one property of the measured rotational speed of the reciprocating piston engine over time.

[0012] In one embodiment of the invention, a method for a reciprocating piston engine is described. The method includes measuring several time intervals, each time interval corresponding to the amount of time the engine needs to rotate through a specified angle. The method further includes determining the frequency content of the several time intervals, calculating a combined value of the amplitudes of the frequency content, a specified harmonic frequency, and diagnosing an engine condition based on the combined value.

[0013] This summary of the invention is provided to introduce, in a simplified form, a selection of concepts that are further described herein. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to limit the scope of protection of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all of the disadvantages specified in any part of this description. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The invention will be understood by reading the following description of non-limiting examples with reference to the accompanying drawings, wherein below: Fig. 1 an illustration of an example embodiment of a vehicle system (e.g. a locomotive system) with a motor and a generator (three-phase generator), which is shown herein as a rail vehicle designed to travel on rails by means of several wheels; Fig. 2. An illustration of an example embodiment of the engine and the generator functionally connected with various auxiliary units and traction motors. Fig. 1 is; Fig. Figure 3 illustrates example implementations of how the frequency content can be generated from the rotational speed of the motor in the time domain; Fig. Figure 4 illustrates what constitutes a “healthy” and “unhealthy” frequency content; Fig. Figure 5 illustrates an example implementation of how a diagnostic logic in the control device can detect an unhealthy condition in the frequency content of an engine speed signal; Fig. Figure 6 illustrates an example implementation of how a time difference (a time interval) can be determined while a motor is rotating; Fig. Figure 7 illustrates an example implementation, such as that achieved using the design of Fig. 6 determined time intervals are to be processed for the diagnosis of an engine condition; Fig. Figure 8 illustrates an example implementation of how an engine condition can be diagnosed by correlating engine speed characteristics and generator characteristics; and Fig. Figure 9 illustrates an example implementation of how to generate a torque profile from the measured rotational speed of a reciprocating engine. DETAILED DESCRIPTION

[0015] Embodiments of the invention described herein relate to systems and methods for diagnosing an engine. Test sets for carrying out the methods are also provided. The engine may be contained in a vehicle, such as a locomotive system. Other suitable types of vehicles include road vehicles, off-road vehicles, mining equipment, aircraft, and ships. Further embodiments of the invention may be used for stationary engines, such as wind turbines or power generators. The engine may be a diesel engine or may burn other fuels or a combination of fuels. Such alternative fuels may include gasoline, kerosene, biodiesel, natural gas, and ethanol, as well as combinations thereof. Suitable engines may use compression and / or spark ignition. These vehicles may contain an engine with components that degrade with use.

[0016] Furthermore, embodiments of the invention described herein use generator data, such as measured electrical parameters of the generator or generator data derived from the measured electrical parameters (e.g. a derived torque profile) and / or motor parameters (e.g. speed) to diagnose the states of a motor and to distinguish between states and associated motor components.

[0017] An engine can be placed in a specific operating state or mode when searching for particular types of engine deterioration. For example, the engine can be diagnosed in a stable operating state during a self-loading condition as part of a test procedure, a dynamic brake (dB) test bench condition, or a monitoring condition. The diagnostic and prognostic methods discussed herein can be used for trend tracking, cylinder / cylinder variation comparison, conducting test procedures, repair confirmation, and repair support. Alternatively, generator and / or engine data can be sampled and analyzed when the engine enters a specific operating state or status during normal operation.

[0018] Fig. Figure 1 illustrates an example embodiment of a vehicle system 100 (e.g., a locomotive system), which is depicted here as a rail vehicle 106 designed for travel on a rail 102 by means of several wheels 108. As shown, the rail vehicle 106 includes a motor 110 functionally connected to a generator (three-phase generator) 120. The vehicle 106 also includes traction motors 130 functionally connected to the generator 120 for driving the wheels 108. Furthermore, the vehicle 106 includes various components functionally connected to the generator 120 or the motor 110 (e.g., the rotatable motor shaft 111, see Figure 1). Fig. 2) Auxiliary systems or units connected for performing various functions 140 .

[0019] The vehicle 106 further includes a control device 150 for controlling various components belonging to the vehicle system 100. In one example, the control device 150 includes a computer control system. In one embodiment, the computer control system is largely software-based and includes a processor, such as a processor 512, configured to execute computer-executable instructions. The control device 150 can include multiple engine control units (ECUs), and the control device system can be distributed across each of the ECUs. The control device 150 further includes computer-readable storage media, such as a memory 154, containing instructions (e.g., computer-executable instructions) to enable on-board monitoring and control of the rail vehicle operation. The memory 154 can include a volatile and a non-volatile memory area.According to another embodiment, the control device can be hardware-based, for example by using digital signal processors (DSPs) or other hardware logic circuitry to perform the various functions described herein.

[0020] The control device can monitor the control and management of the vehicle system 100. The control device can receive a signal from a speed sensor 160 of the motor or from various generator sensors 170 to determine operating parameters and operating conditions and accordingly adjust various motor actuators 162 to control the operation of the rail vehicle 106. According to one embodiment, the speed sensor includes a multi-toothed sensor wheel connected to the motor shaft 111 and a reluctance sensor for measuring when a tooth of the sensor wheel passes the reluctance sensor. For example, the control device can receive signals representing various generator parameters from different generator sensors. The generator parameters can 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 control device can control the vehicle system by sending commands to various components, such as traction motors, the three-phase generator, cylinder valves, throttle valve, etc. Signals from the generator sensors 170 can be bundled into one or more wiring harnesses to reduce the space required for wiring in the vehicle system 100 and to protect the signal wires from abrasion and vibration.

[0021] The control device can include onboard electronic diagnostics for recording engine operating characteristics. These operating characteristics can include, for example, measured values ​​from sensors 160 and 170. In one embodiment, the operating characteristics can be stored in a database in memory 154. In another embodiment, current operating characteristics can be compared with previous operating characteristics to determine trends in the operating behavior of the engine and / or auxiliary units.

[0022] The control device may include onboard electronic diagnostics for identifying and recording potential deterioration and faults of components of the vehicle system 100. For example, if a potentially deteriorated component is identified, a diagnostic code may be stored in memory 154. In one embodiment, a unique diagnostic code may correspond to each type of deterioration that can be identified by the control device. For example, a first diagnostic code may indicate a problem with cylinder 1 of the engine, and a second diagnostic code may indicate a problem with cylinder 2 of the engine.

[0023] The control device can also be linked to a display device 180, such as a diagnostic interface display device, which provides a user interface for the locomotive operating and maintenance crews. The control device can control the engine in response to user input via user input controls 182 by sending a command to adjust various engine actuators 162 accordingly. Non-limiting examples of user input controls 182 may include a throttle control device, a brake control device, a keypad, and a circuit breaker. Furthermore, operating characteristics of the engine, such as diagnostic codes corresponding to deteriorated components, can be reported to the operator and / or maintenance crews via the display device 180.

[0024] The vehicle system can include a communication system 190 connected to the control device. In one embodiment, the communication system 190 can include a radio device and an antenna for transmitting and receiving voice and data messages. For example, data communication can take place between the vehicle system and a railway control center, another locomotive, a satellite, and / or a trackside device, such as a track switch. For example, the control device can estimate the geographical coordinates of the vehicle system using signals from a GPS receiver. As another example, the control device can transmit operating characteristics of the engine to the control center via a message sent by the communication system 190.In one embodiment, a message can be transmitted to the command center via the communication system 190 when a deteriorated component of the engine is detected and the vehicle system can be scheduled for maintenance.

[0025] Fig. Figure 2 illustrates an example embodiment of the motor 110 and the generator 120, which is functionally connected to various auxiliary units 140 (141, 142, 143, 144) and to the traction motors 130. Fig. 1. The various mechanical auxiliary units 144 can be functionally connected to and driven by the rotating motor shaft 111. Further auxiliary units 140 are driven by the generator 120 via a rectifier 210, which generates a DC intermediate voltage for current controllers 230. Examples of such auxiliary units include a blower 141, a compressor 142, and a radiator fan 143. The traction motors 130 are driven by the generator 120 via the rectifier 210, which generates a DC intermediate voltage at a converter 220. Such auxiliary units 140, traction motors 130, and their implementations are well known in the field.

[0026] According to certain embodiments, the generator 120 can actually be one or more generators, such as a main generator for driving the traction motors 130 and an auxiliary generator for operating some of the auxiliary equipment 140. Furthermore, examples of auxiliary equipment include turbochargers, pumps, and engine cooling systems.

[0027] The speed sensor 160 measures the rotational speed of the motor's rotating shaft 111 during operation. The DC link sensor 171 is a generator sensor and can measure a DC link voltage, a DC link current, or both, according to various embodiments. The field sensor 172 is a generator sensor and can measure the generator's field current, generator's field voltage, or both, according to various embodiments. Generator sensors 173 and 174 are provided for measuring the armature output voltage and generator current, respectively, according to various embodiments. Suitable commercially available sensors can be selected based on application-specific parameters.

[0028] An engine can contain multiple cylinders that fire in a predetermined sequence, with each cylinder firing once during a four-stroke or two-stroke cycle. For example, a four-cylinder, four-stroke engine might have a firing sequence of 1-3-4-2, with each cylinder firing once every two engine revolutions. Thus, the firing frequency of a given cylinder is half the engine's rotational frequency, and the firing frequency of all cylinders is twice the engine's rotational frequency. The engine's rotational frequency can be described as the first engine order. Such a first-order frequency component may appear in the frequency content of the measured generator parameter. The firing frequency of a given cylinder in a four-stroke engine can be described as half the engine order, where half the engine order is half the engine's rotational frequency.Such a half-order frequency component can appear in the frequency content of the measured generator parameter.

[0029] As another example of a four-stroke engine, a twelve-cylinder engine can have a firing sequence of 1-7-5-11-3-9-6-12-2-8-4-10, with each cylinder firing once every two engine revolutions. Thus, the firing frequency of a given cylinder is half the engine's revolution frequency, and the firing frequency of all cylinders is six times the engine's revolution frequency. As an example of a two-stroke engine, a twelve-cylinder engine can have a firing sequence of 1-7-5-11-3-9-6-12-2-8-4-10, with each cylinder firing once per engine revolution. Thus, the firing frequency of a given cylinder is the engine's revolution frequency, and the firing frequency of any given cylinder is twelve times the engine's revolution frequency. Again, these frequency components can appear in the frequency content of the measured generator parameter.

[0030] For example, the motor could be a four-stroke engine operating at 1050 RPM. Thus, the first motor order is at 17.5 Hz and the second motor order is at 8.75 Hz. The DC link voltage can vary with a periodic frequency as the motor shaft 111 rotates during operation. For example, the frequency content of the DC link voltage can include a frequency component at the frequency of the first motor order. In other words, the peak magnitude of the frequency content can appear at the first-order frequency component. The DC link voltage can also contain frequency content at other harmonics of the first order, such as a second-order frequency (twice the motor frequency), a third-order frequency (three times the motor frequency), and so on. Likewise, the DC link voltage can contain frequency content at frequencies lower than the first order, such as...at half the frequency (half the motor frequency).

[0031] For a motor that is "healthy" and functioning correctly, the frequency content of the measured parameters can have a specific healthy signature. Deviations from such a healthy signature can indicate a problem with the motor. For example, according to one embodiment, a motor's condition can be diagnosed by analyzing a magnitude and / or phase of the half-order frequency content.

[0032] In general, according to various embodiments, a motor condition can be diagnosed based on a combination of measured parameters from the motor (e.g., speed or pressure) and the generator (e.g., DC link voltage, etc.). The frequency content of the various parameters can be determined and compared to diagnose a specific motor condition. Furthermore, additional parameter profiles (e.g., torque) can be estimated from the measured parameter profiles, and the frequency content of these profiles can then be analyzed to diagnose a specific motor condition.

[0033] In one embodiment, the frequency content of the motor's rotational speed (e.g., where the rotational speed is measured using the speed sensor 160) is used to diagnose the condition of a motor. Fig. Figure 3 is a representation of example implementations for generating the frequency content from the motor's rotational speed in the time domain. A Fourier transform process 310 (e.g., a fast Fourier transform, FFT, process) or a bandpass filtering process 320 can be used to extract the harmonic content. The frequency analysis process transforms the sampled time-domain parameters into a frequency content in the frequency domain. The various frequency components of the frequency content can include DC (zero order), fundamental (first order), and harmonic (second order, half order, third order, etc.) frequency components. According to one embodiment, the Fourier transform process and the bandpass filtering process include computer-executable instructions that are executed by the processor 152.

[0034] Fig. Figure 4 is a representation showing exemplary embodiments of a “healthy” and “unhealthy” frequency content. According to one embodiment, the frequency content 410 of the healthy motor (i.e., a motor that operates properly) has three frequency components of absolute and relative magnitudes as shown in Fig. Figure 4 illustrates this. The frequency content 420 of the unhealthy engine (i.e., an engine that is not operating properly due to a specific deterioration or fault) has three frequency components in the same positions as in the frequency content 410 of the healthy engine. However, the amplitude of one frequency component 421 (i.e., a half-order component) is distorted (e.g., increased in amplitude), and the amplitude of another frequency component 423 (e.g., the second-order component) is also distorted (i.e., decreased in amplitude). The distorted frequency components 421 and 423 in the frequency content 420 indicate an unhealthy engine. Furthermore, the specific characteristics of the distorted frequency components (e.g., the amplitude) relative to the other frequency components in the frequency content 420 of the unhealthy engine can indicate a specific type of engine deterioration or fault (e.g.,The phase of the component, measured against a reference cylinder (e.g., cylinder number 1), can also be used to isolate the problem to a specific cylinder.

[0035] Deteriorated components can cause the engine to operate less efficiently, with reduced power, and / or increased fouling. Furthermore, the condition of deteriorated components can accelerate their deterioration, increasing the likelihood of catastrophic engine failure and track downtime. A deteriorated engine cylinder is an example of a deteriorated engine component. For example, in a four-stroke engine, the distorted frequency component might be at half the frequency. In a two-stroke engine, the distorted frequency component might be at first the frequency. The diagnostic system can then include, for example, a warning about the deterioration as well as an indication of the type and / or location of the deteriorated engine component.

[0036] Fig. Figure 5 is a representation of an embodiment in which a diagnostic logic 510 in the control device 150 can detect an unhealthy condition in the frequency content of an engine speed signal. For example, the diagnostic logic 510 can compare the half-order component 421 with a threshold value T. If the magnitude of component 421 exceeds the threshold value T, the diagnostic logic 510 determines that deterioration has occurred in the engine. Furthermore, if the diagnostic logic 510 determines that the ratio of the half-order component to the first-order component 422 exceeds a second threshold, and the ratio of the first-order component to the second-order component 423 exceeds a third threshold, then the diagnostic logic 510 isolates the deterioration to a specific engine component (e.g., cylinder number 3).According to one embodiment, the diagnostic logic includes computer-executable instructions that are executed by the processor 152. According to one embodiment, the ratio of a half-order component to a zero-order component (DC) can indicate a motor problem. Furthermore, the threshold level T can depend on an operating condition of the motor, such as power, speed, environmental conditions, repair history, etc.

[0037] Types of engine deterioration or faults that can be diagnosed, differentiated, and isolated include, for example, a worn spark plug, uneven fuel distribution, a faulty cylinder, engine knocking, insufficient fuel supply, low compression, and a valve train fault. Once a deterioration or fault is diagnosed, action can be taken. Such actions may include, for example, generating a warning signal for the operator (e.g., via indicator 180), adjusting an engine operating parameter (e.g., reducing engine power, shutting down at least one cylinder, shutting down the engine completely, or balancing the cylinders), recording a maintenance action, and transmitting the diagnosed condition to a central location (e.g., via the communication system).

[0038] Therefore, the harmonic content (magnitudes and / or phases) of the engine speed can be analyzed (e.g., using the control device's diagnostic logic 510) to determine engine deterioration. According to one embodiment, the reciprocating engine is first brought into a specified operating condition, status, or mode before the engine speed information is sampled and processed. According to another embodiment, the engine speed information is not sampled and processed until the engine reaches a predetermined operating condition, status, or mode during normal operation, at which point the control device is instructed to extract and analyze the harmonic content of the engine speed when the specified condition, status, or mode is reached.

[0039] In one embodiment, the difference in the measured rotational speed of the reciprocating engine from cycle to cycle (where the speed is measured by the speed sensor 160) is used to diagnose the condition of the engine. A cycle can correspond to a complete rotation or revolution of the engine. However, according to various embodiments, a cycle can also be defined differently. For example, a cycle can be two full revolutions of the engine (which may correspond to one firing cycle of a single cylinder), or a cycle can be half a revolution of the engine (which may correspond to the firing frequency of all cylinders of the engine).

[0040] Since the rotational speed varies from cycle to cycle, characteristics (e.g., harmonic content) of the cycle-to-cycle differences can be analyzed and correlated with a deteriorating engine condition. In one embodiment, the reciprocating engine can first be brought into a specified operating state, status, or mode before the engine speed information is sampled and processed. In another embodiment, the engine speed information is not sampled and processed until the engine reaches a predetermined operating state, status, or mode during normal operation, at which point the control device is instructed to extract and analyze the engine speed difference when the specified state, status, or mode is reached.

[0041] In one embodiment, the time difference for a reciprocating engine to rotate through a predetermined angle is used to diagnose the condition of the engine. The predetermined angle can be, for example, a full 360-degree rotation of the engine (cycle to cycle) or a specific smaller angle. Fig. Figure 6 shows an example embodiment of how such a time difference (a time interval) can be determined. A toothed wheel 610 is connected to the rotating shaft 111 of the motor and rotates with the shaft 111. A sensor 620 (e.g., a reluctance sensor) is positioned next to the toothed wheel 1010 and is capable of measuring when a tooth of the wheel 610 passes the sensor 620 as the wheel 610 rotates. A time-domain signal from the sensor 620 is supplied to the control device 150. The control device can be operated to sample the signal and determine the time difference between each measured tooth. The angular difference between adjacent teeth on the wheels corresponds to a predetermined angle. Therefore, the angular difference between any two teeth on the wheel corresponds to a certain predetermined angle.According to one embodiment, the control device is designed to determine the time required for the sensor to pass through each pair of adjacent teeth.

[0042] For example, when the wheel 610 rotates, the time difference (time interval) ΔT1 between tooth 1 and tooth 2 is determined, the time difference ΔT2 between tooth 3 and tooth 4 is determined, the time difference ΔT3 between tooth 5 and tooth 6 is determined, etc., while the wheel rotates and the sensor 620 detects the passing individual teeth. Fig. Figure 7 illustrates an example implementation of how to process time intervals using the configuration of Fig. 6 were determined to diagnose an engine condition.

[0043] According to Fig. 7. The time-domain samples of the time intervals (ΔT1, ΔT2, ΔT3, ...) are processed (for example, by an FFT process 310 of the control device) to determine the frequency content. A combined value (a root mean square (RMS) or an average value) of the frequency content amplitudes around a specified harmonic frequency (e.g., around the half-order frequency) is calculated by an RMS process 710 of the control device 150. The frequency content may be present at and near the specific harmonic frequency (e.g., the half-order frequency) due to load and speed fluctuations. A motor condition is diagnosed by a comparison process 710 of the control device based on the combined value (e.g., by comparing the combined value with a threshold value).Several threshold values ​​can be provided, each corresponding to a different severity of the deteriorating engine condition. Depending on the severity, different actions can be taken (e.g., scheduling a maintenance action, reducing engine power, or shutting down the engine).

[0044] In one embodiment, the reciprocating engine can first be brought into a specified operating state, status, or mode before the time intervals are sampled and processed. In another embodiment, the time interval information is not sampled and processed until the engine reaches a predetermined operating state, status, or mode during normal operation, at which point the control device is instructed to determine and analyze the time interval information.

[0045] Fig. Figure 8 shows an example implementation of how a motor condition can be diagnosed by mutually correlating motor speed characteristics and generator characteristics. The speed of the motor 110 is measured over time (e.g., using the speed sensor 160), and the electrical parameters associated with the generator 120 are measured over time. The control device 150 has a correlation process 810, which correlates characteristics of the measured speed with characteristics of the measured electrical parameters. Based on the resulting correlations, a motor condition is diagnosed. Just as the harmonic content of a time-domain speed signal from the motor can be determined, for example, by using an FFT process or a bandpass filtering process, the harmonic content of a time-domain generator parameter can be determined in a similar way.

[0046] The speed characteristics can include at least one of the speed's harmonic content, the cycle-to-cycle variation in the measured speed, a torque profile derived from the speed, and the time difference for the reciprocating motor to rotate through a predetermined angle. The measured electrical parameters can 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. Characteristics of the electrical parameters can include, for example, a harmonic content of one or more of the parameters or the torque profile derived from one or more of the parameters. According to one embodiment, the contribution of torque disturbances caused by a connected load (e.g.,a sixth harmonic torque generated by a rectifier) ​​is removed or ignored as part of the process.

[0047] As an example, a half-order component of the DC link voltage can be correlated with a half-order component of the speed signal for diagnostic purposes. If the amplitude of the half-order component of the DC link voltage is above a first threshold and the phase of the half-order component of the speed signal is between a second or third threshold (with respect to a specific reference value), then the engine diagnosis could be a fuel supply problem in a particular cylinder.

[0048] As another example, a first-order component of the generator field current can be correlated with a second-order component of the speed signal. If the amplitude of the first-order component of the field current is less than a first threshold, and if the amplitude of the second-order component of the speed signal is greater than a second threshold, then the diagnosis could be that the engine has a low compression problem. However, if the amplitude of the first-order component of the field current is greater than the first threshold, and the amplitude of the second-order component of the speed signal is still greater than the second threshold, then the diagnosis could be a faulty spark plug. Many other correlations or corresponding diagnoses are also possible.

[0049] According to one embodiment, the reciprocating engine can first be brought into a specified operating state, status, or mode before the correlation process 810 is executed. According to another embodiment, the correlation process is not carried out until the engine reaches a predetermined operating state, status, or mode during normal operation, at which point the control device is instructed to perform the correlation process with respect to the speed and generator characteristics.

[0050] In one embodiment, a test set is provided with a control device that determines the condition of a reciprocating engine based on at least one property of a measured rotational speed of the engine over time. The test set can further include one or more sensors for measuring electrical parameters associated with a generator, which are functionally connected to the engine during operation. The control device can be operated to communicate with the one or more sensors for sampling the electrical parameters over time. The control device can also be operated to correlate properties of the measured rotational speed and properties of the electrical parameters to diagnose the engine's condition.

[0051] Fig.Figure 9 shows an example embodiment of how to diagnose a torque profile from the measured rotational speed of a reciprocating engine. The control device 150 implements a torque estimation process 910, which samples the engine's rotational speed (from the speed sensor 160) over time, derives acceleration components (taking into account the derivative of the rotational speed with respect to time) from the measured rotational speed at predetermined characteristic frequencies, and combines the acceleration components to determine a torque profile. The engine is then analyzed by examining properties of the torque profile. For example, harmonic components of the torque profile can be generated and compared with threshold values. Again, according to one embodiment, the reciprocating engine is first brought into a specified operating state, status, or mode before the torque estimation process 910 is performed.According to another embodiment, the torque estimation process is not carried out until the motor reaches a predetermined operating condition, status or mode during normal operation, at which point the control device is prompted to perform the torque estimation process and the subsequent analysis of the estimated torque profile.

[0052] According to various embodiments, the control device 150 can be operated in such a way that it reports a deteriorated engine condition, for example, via the communication system 190. Furthermore, according to various embodiments, the control device includes instructions configured to adjust an engine operating parameter based on the diagnosed condition.

[0053] Further examples of applications of the systems and methods described herein are now provided. These examples illustrate various approaches to diagnosing and differentiating between different types of motor deterioration based on the frequency content of generator data (e.g., a relatively coarse generator parameter such as a DC link voltage or other derived generator parameters such as electromagnetic torque) that are associated with the generator or the motor speed during motor operation.

[0054] In one embodiment, a deteriorated cylinder of a four-stroke engine can be detected based on a frequency content signature, such as when the magnitude of the half-order component is greater than a half-order threshold. In an alternative embodiment, the frequency content magnitudes can be integrated over the frequency range, and a deteriorated cylinder of a four-stroke engine can be detected based on the fact that the integration value is greater than an integral threshold.

[0055] Detecting only one degraded cylinder, while the other cylinders in the engine are in better condition (or less degraded), can result in a more pronounced frequency content signature than detecting degraded cylinders in multiple cylinders. For example, the frequency content signature of the single degraded cylinder can be identified by comparing the magnitude of its half-order frequency component to a half-order magnitude threshold. However, multiple degraded cylinders may have a different frequency component signature than just one. Furthermore, the firing order of multiple degraded cylinders can alter their frequency content signature.For example, two cylinders out of phase by 180 degrees may have a different frequency component signature than two deteriorated cylinders in successive firing order, and thus the methods disclosed herein can identify one or more deteriorated cylinders based on various changes in the frequency content signature. Furthermore, it can be useful to generate a frequency content signature of a healthy engine by recording the frequency content at different frequencies and operating conditions. In one embodiment, the engine's frequency content can be compared to the frequency content signature of a healthy engine. Anomalies that do not match the frequency content signature of the healthy engine or any other deteriorated engine component can, for example, be identified and reported by the control device.Other examples of deteriorated engine components include a deteriorated crankcase ventilation system, a deteriorated turbocharger, and a deteriorated crankcase.

[0056] In one embodiment, the time-domain generator data can be filtered by a low-pass filter with a cutoff frequency slightly higher than the first-order frequency of the motor. For example, the cutoff frequency can be 10 to 20 percent higher than the first-order frequency. Thus, in one embodiment, the cutoff frequency can be determined by the motor speed. The generator data can be sampled at a frequency higher than or equal to the Nyquist rate. In one embodiment, the time-domain signal can be sampled at a frequency higher than twice the first-order frequency of the motor. In another embodiment, the time-domain signal can be sampled at a frequency higher than twice the cutoff frequency of the motor.

[0057] Therefore, by using low-pass filtering and sampling at a frequency higher than or equal to the Nyquist rate, the frequency content of the generator data cannot be distorted. The same applies to the motor's speed data.

[0058] As discussed herein, the sampled generator data (e.g., DC link voltage, torque, etc.) and / or the sampled motor speed data can be transformed to generate a frequency-domain frequency content. In one embodiment, a fast Fourier transform can be used to generate the frequency-domain frequency content. In another embodiment, a correlation algorithm can be applied to compare the frequency content of the data with a signature for a motor condition. For example, the signature for a healthy motor might include a frequency content at the first-order frequency with a magnitude below a first-order threshold and a frequency content at the half-order frequency with a magnitude below a half-order threshold. The first-order threshold might correspond to the motor speed, motor load, crankshaft temperature, and historical motor data.

[0059] For example, historical engine and generator data can be stored in a database containing samples of the frequency content from previous engine operation. This allows for the detection of a trend in the frequency content, which can then be used to determine the engine's health. For instance, an increasing magnitude in the engine's half-order component for a given engine speed and load might indicate cylinder deterioration. Similarly, an increasing average crankcase pressure, in conjunction with an increasing magnitude in the engine's half-order component for a given engine speed and load, might indicate turbocharger or crankcase ventilation system deterioration. A potential fault could involve a deteriorated cylinder, a deteriorated turbocharger, or a deteriorated crankcase ventilation system.

[0060] In one embodiment, the frequency content of the generator data and / or the engine speed data can be stored in a database containing historical engine and generator data. For example, the database can be stored in memory 154 of the control device 150. As another example, the database can be stored at a location outside the rail vehicle 106. For example, historical data can be included in a message and transmitted via a communication system 190. In this way, a control center can monitor the engine's health in real time. For example, the control center can perform steps to diagnose the engine's condition using the generator / speed data transmitted via the communication system 190.For example, the control center can receive data from the rail vehicle 106, perform a frequency transformation of the data, apply a correlation algorithm to the transformed data, and diagnose potential engine deterioration. Furthermore, the control center can schedule maintenance and deploy fault-free locomotives and maintenance personnel in a manner that optimizes capital investment. Historical data can also be used to assess engine health before and after engine servicing, engine modifications, and engine component replacements.

[0061] In one embodiment, a potential fault can be reported to the locomotive operating crew via a display device 180. This report allows the operator to adjust the operation of the rail vehicle 106 to reduce the possibility of further engine deterioration. In another embodiment, a message indicating a potential fault can be sent to a control center via the communication system 190. Furthermore, the severity of the potential fault can be reported. For example, diagnosing a fault based on a comparison of the frequency content of generator data and / or engine speed data can enable earlier fault detection than if the fault is diagnosed using only average engine information (e.g., only the speed information). Thus, the engine can continue operating if a potential fault is diagnosed in the early stages of deterioration.In contrast, it may be desirable to stop the engine or schedule immediate maintenance if a potential fault is diagnosed as severe. In one embodiment, the severity of a potential fault can be determined based on the difference between a threshold value and the magnitude of one or more components of the frequency content of the generator and / or speed data.

[0062] By analyzing the frequency content of the generator and / or speed data, it may be possible to monitor and diagnose the engine during operation. Furthermore, the operation of an engine with a deteriorated component can be adjusted to potentially reduce further deterioration of the engine component and thus the likelihood of additional engine failures and operational malfunctions. For example, the component's half-order deterioration can be compared to a half-order threshold. In one embodiment, if the component's half-order deterioration is greater than the half-order threshold, the potential failure could be a deteriorated cylinder. However, if the component's half-order deterioration is not greater than the half-order threshold, the potential failure could be a deteriorated turbocharger or a deteriorated crankcase ventilation system.

[0063] In one embodiment, the potential fault can be reported to the locomotive operating crew by means of a display device 180, and the operator can adjust the operation of the rail vehicle 106 to reduce the possibility of further deterioration. In another embodiment, a message diagnosing the potential fault can be transmitted to a control center via the communication system 190.

[0064] In one embodiment, an engine operating parameter can be adjusted to identify a deteriorating cylinder. For example, the deteriorating cylinder can be identified based on the selective deactivation of fuel injection to one or more cylinders of the engine. In one embodiment, fuel injection for each cylinder can be deactivated sequentially from the multiple cylinders, while one or more of the generator and / or speed data elements and the associated frequency content are monitored. For example, fuel injection to one cylinder can be deactivated while the other cylinders operate normally. By deactivating each cylinder in a sequence, the deteriorating cylinder can be identified. As another example, fuel injection to a group of cylinders can be deactivated while the other cylinders operate normally.By means of a cycle through different groups in a sequence, the deteriorated cylinder can be identified through an elimination process.

[0065] In one example, the half-order frequency component of the generator and / or the speed data can be observed for each deactivated cylinder of a four-stroke engine. The deactivated cylinder may be a degraded cylinder if the half-order frequency component falls below a half-order threshold while the cylinder is deactivated. The deactivated cylinder may be a healthy cylinder if the half-order frequency component remains above the half-order threshold while the cylinder is deactivated. In other words, the degraded cylinder may be the cylinder that contributes a higher amount of frequency content in the half-order frequency component than other cylinders. In one embodiment, the diagnosis with selective deactivation can be performed when the engine is running at idle or light load.

[0066] In one embodiment, the diagnosis of selective deactivation can further be performed based on the frequency content of engine operating parameters, such as engine speed. For example, the engine speed may contain a frequency component in the half-order range when a deteriorated cylinder is operating. Thus, observing the frequency content of various engine operating parameters while simultaneously selectively deactivating each cylinder can identify the deteriorated cylinder.

[0067] In one embodiment, the deteriorating cylinder can be identified based on a selective change in fuel injection to one or more cylinders of the engine. For example, the fuel supply to each cylinder can be selectively increased or decreased while simultaneously monitoring the half-order frequency component of the generator and / or the engine speed data. Furthermore, the signature, for example, the frequency content, of each cylinder can be compared with historical data for the engine or with that of a healthy engine. For example, the diagnostic test can be performed on a healthy engine to generate a baseline measurement signature. The baseline measurement signature can then be compared with the frequency content during engine diagnostics. In another embodiment, the deteriorating cylinder can be identified by changing the engine fuel injection timing.For example, advance angle adjustments can be used to diagnose the deteriorating cylinder. For instance, the engine fuel injection timing can be delayed to potentially increase the frequency content of the half-order frequency component.

[0068] It may be preferable to shut down the engine rather than have the deteriorating cylinder fail in a way that could cause further damage to the engine. In one embodiment, a threshold can be determined to indicate that continued operation of the engine may be undesirable because the potential fault is severe. For example, the potential fault may be judged to be severe if the magnitude of the half-order frequency component exceeds a threshold. The engine can be stopped if the severity of the potential fault exceeds the threshold.

[0069] A service planning request can be sent, for example, via a message transmitted through the 190 communication system. Furthermore, the downtime of rail vehicle 106 can be reduced by transmitting the potential fault condition and its severity. For example, service on rail vehicle 106 can be postponed if the potential fault is of minor severity. Downtime can also be reduced by reducing the engine's power output, such as by adjusting an engine operating parameter based on the diagnosed condition. It can be determined whether engine power reduction is activated. For example, engine power reduction can reduce the magnitude of one or more components of the generator's frequency content and / or speed data.

[0070] An engine operating parameter can be adjusted to, for example, reduce further deterioration of the already deteriorated component. In one embodiment, the engine speed or power output can be limited. In another embodiment, fuel injection into the potentially deteriorated cylinder can be reduced or deactivated while the other cylinders continue to operate. This allows the engine to continue running and reduces further deterioration of the deteriorated cylinder. In this way, the engine can be adjusted to potentially prevent further deterioration of the engine component and potentially reduce the likelihood of catastrophic engine failure and track downtime.

[0071] In one embodiment, a test set can be used to identify the generator and / or speed data and to diagnose the condition of the motor based on the frequency content of the data. For example, a test set can include a control device that can be operated to communicate with one or more generator or motor sensors and to sample the associated data. The control device can further be operated to transform signals from one or more sensors into a frequency content that represents frequency information of the motor. The control device can further be operated to diagnose the condition of the motor based on the frequency content of the sampled data from the sensor(s). The test set can also include one or more sensors for measuring generator parameters (e.g., generator output voltage) and / or motor parameters (e.g.,(includes engine speed).

[0072] The description and claims refer to a number of terms that have the meanings listed below. The singular forms "a" and "the" include plural references unless the context clearly indicates otherwise. Approximate language, as used throughout the description and claims herein, can be applied to modify any quantitative representation that may permissibly vary without altering the basic function to which it refers. Accordingly, a value modified by a term such as "approximately" is not limited to the stated exact value. In some cases, the approximate language may correspond to the accuracy of an instrument used to measure the value.Similarly, "free from" may be used in combination with a term and may include an insignificant number or trace amounts while simultaneously being considered free from the modified term. Furthermore, unless specifically stated otherwise, any use of the terms "first," "second," etc., does not denote any order or importance, but instead is intended to distinguish one element from another.

[0073] As used herein, the terms "may" and "may be" indicate a possibility of occurrence within a set of circumstances; of possession of a specified property, characteristic, or function; and / or qualify another verb by expressing one or more of an ability, suitability, or possibility associated with the qualifying verb. Accordingly, the use of "may" and "may be" indicates that a modified term is evidently appropriate, suitable, or fit for a specified ability, function, or use, while acknowledging that under certain circumstances the modified term may sometimes not be appropriate, suitable, or fit.For example, under certain circumstances an event or capability may be expected, while under other circumstances the event or capability may not be present—this distinction being captured by the terms "may" and "may be." The terms "generator" and "three-phase generator" are used interchangeably herein (although it is apparent that one or the other may be more appropriate depending on the application). 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 components. The term "instructions," as used herein in relation to a control device or processor, may refer to computer-executable instructions.As used herein, the terms “speed”, “speed data” and “speed signal” may refer to any speed of a motor, harmonic content of a measured motor speed, a difference in a measured motor speed from cycle to cycle, a difference in times for a motor to rotate through a predetermined angle, and multiple time intervals, each time interval representing a time required for a motor to rotate through a predetermined angle.

[0074] The embodiments described herein are examples of objects, systems, and methods that correspond to the elements of the invention as set forth in the claims. This description may enable a person skilled in the art to carry out and use embodiments with alternative elements that also correspond to the elements of the invention as set forth in the claims. The scope of protection of the invention thus includes objects, systems, and methods that do not differ from the wording of the claims and further includes other objects, systems, and methods with insignificant differences from the wording of the claims. Although only certain features and embodiments of the invention have been presented and described herein, many modifications and changes will be apparent to a person skilled in the art. The appended claims cover all such modifications and changes.

Claims

[1] Method for a reciprocating piston engine (110), comprising the steps: Diagnosing a condition of the engine (110), characterized by , that Diagnosis is based on: a time difference for the reciprocating engine (110) to rotate through a predetermined angle from cycle to cycle. [2] A method for a reciprocating engine (110) operatively connected to a generator (120), comprising the steps of: Measuring a speed of the reciprocating piston engine (110) over time; Measuring electrical parameters associated with the generator (120) over time; Correlating properties of the measured speed with properties of the measured electrical parameters; and Diagnosing a condition of the engine (110) based on the correlated properties. [3] The method of claim 2, wherein characteristics of the measured speed include at least one of a harmonic content (420) of the speed, a cycle-to-cycle difference in the measured speed, and differences in the measured times for the reciprocating engine (110) to rotate through a predetermined angle. [4] The method of claim 2, wherein the measured electrical parameters include at least one of an output current of the generator (120), an output voltage of the generator (120), a field current of the generator (120), a field voltage of the generator (120), a current of a DC link (171), and a voltage of the DC link (171). [5] Method for a reciprocating piston engine (110), comprising the steps: Determining a speed of the reciprocating piston engine (110) over time; Determining a torque profile by combining acceleration components derived from the measured speed at certain characteristic frequencies; and Diagnosing a condition of the engine (110) based on characteristics of the torque profile. [6] Vehicle system (100), comprising: an engine (110); a sensor (160) for measuring the speed of the reciprocating engine (110); and a control device (150) having instructions configured to sample the measured speed and determine a state of the engine (110) based on: a time difference required for the motor (110) to rotate through a predetermined angle. [7] The vehicle system (100) of claim 6, wherein the control device (150) is operable to report a degraded condition of the engine (110). [8] The vehicle system (100) of claim 6, wherein the controller (150) further includes instructions configured to adjust an operating parameter of the engine (110) based on the diagnosed condition. [9] Vehicle system (100), comprising: an engine (110); a generator (120) operatively connected to the engine (110); a sensor (160) for measuring a rotational speed of the reciprocating engine (110) over time; Sensors (170) for measuring electrical parameters associated with the generator (120) during operation; and a control device (150) having instructions configured to sample the measured speed and the measured electrical parameters and to diagnose a condition of the engine (110) based on correlations between characteristics of the measured speed and characteristics of the electrical parameters of the generator (120). [10] The vehicle system (100) of claim 9, wherein the control device (150) is operable to report a degraded condition of the engine (110). [11] The vehicle system (100) of claim 9, wherein the controller (150) further includes instructions configured to adjust an operating parameter of the engine (110) based on the diagnosed condition. [12] Method for a reciprocating piston engine (110), comprising the steps of: measuring a plurality of time intervals, each time interval corresponding to a time required for a motor (110) to rotate through a specified angle; Determining a frequency content (420) of the plurality of time intervals; Calculating a combined value of the amplitudes of the frequency content (420) around a specified harmonic frequency (421); and Diagnosing a condition of the engine (110) based on the combined value.

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