System and procedure for engine diagnostics

Abstract

Method for an engine having a crankcase, comprising: - Diagnosing, by means of a control device, a condition of the engine based on a frequency content of a measured crankcase pressure, wherein the diagnosis of the engine condition includes determining whether there is a functional deterioration of an engine cylinder and a component related to the engine cylinder, wherein this component is a turbocharger; wherein the method further comprises: - Adjusting an engine operating parameter via the control unit based on the diagnosed condition; and - furthermore, correlating crankcase pressure information with one of the following: crankshaft position, camshaft position, fuel injection sequence.

Description

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

[0002] Engine components can deteriorate in various ways during operation. For example, the sealing effect of piston rings on the piston in the combustion chamber can decrease, resulting in increased blowby of combustion gases into the engine crankcase.

[0003] One method for detecting engine deterioration is monitoring the equilibrium crankcase pressure. Diagnostic routines can observe whether the crankcase pressure rises above a threshold and generate diagnostic codes or other indications that require service, a derating of engine power, or engine shutdown.

[0004] Generic methods are known in the prior art, for example from US 4 424 709 A, US 7 954 363 B2, US 5 402 675 A, US 6 779 388 B2 or US 6 338 250 B1.

[0005] However, the inventors have recognized that an increase in equilibrium crankcase pressure can be caused by a number of different degraded components, and it can be time-consuming for a maintenance team to determine the source of the degraded component during engine maintenance and whether the increased piston blowby is indeed the source of the degradation. TASK

[0006] It is the object of the present invention to further develop a method of the type mentioned at the outset in an advantageous manner, in particular to the effect that an engine can be maintained more easily and efficiently.

[0007] This object is achieved according to the invention by the features of the independent claims. Further advantageous embodiments of the invention are the subject of the dependent claims. SHORT DESCRIPTION

[0008] In one embodiment, a method for an engine is provided. The method includes diagnosing a condition of the engine based on a frequency content of the crankcase pressure.

[0009] In one embodiment, a method for an engine is provided. The method includes distinguishing between different types of degradation based on a frequency content of the crankcase pressure.

[0010] A deteriorating engine component can be diagnosed during engine operation. For example, it may be possible to distinguish between different types of deterioration by examining the frequency content of the crankcase pressure, providing maintenance teams with additional information about the source of the deterioration. Furthermore, a specific cylinder that is no longer fully functional can be identified from the frequency content of the crankcase pressure during engine operation, which in turn provides additional diagnostic and prognostic information for maintenance teams. In this way, maintenance-related delays can be reduced because the source of the deterioration and the specific cylinder that is no longer fully functional can be identified prior to maintenance.

[0011] 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

[0012] The invention will become apparent from reading the following description of non-limiting embodiments with reference to the accompanying drawings, in which: Fig. 1 shows an embodiment of a vehicle having an engine with a crankcase. Fig. 2 shows an embodiment of a cylinder of the engine during the compression stroke. Fig. 3 shows an embodiment of a cylinder of the engine during the power stroke. Fig. Figure 4 shows data from a time-domain crankcase pressure signal. Fig. 5 and Fig. 6 each showed data from a frequency domain crankcase pressure signal. Fig. 7 and Fig. 8 each show an embodiment of a method for diagnosing a condition of the engine. DETAILED DESCRIPTION

[0013] Embodiments of the subject matter disclosed herein relate to a system and method for engine diagnostics. A test kit for performing the method is 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, and marine vessels. Other embodiments of the invention may be used for stationary engines. The engine may be a diesel engine, or it may burn 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 include an engine with components that wear out with use.Engine cylinder components, such as piston rings, can deteriorate. This deterioration can lead to or cause increased blowby. As blowby increases, a corresponding and measurable increase in unburned fuel and / or exhaust gases escaping from the area surrounding the piston and into the crankcase can occur.

[0014] Fig. 1 is an illustration of an 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 a motor system having an engine 110.

[0015] The engine receives intake air for combustion from an intake line 114. The intake line 114 receives outside air from outside the rail vehicle 106. Exhaust gas resulting from combustion in the engine is delivered to an exhaust line 116. Exhaust gas flows through the exhaust line 116 and out an exhaust stack of the rail vehicle 106.

[0016] The engine system includes a supercharger 120 (TURBO) disposed between the intake passage 114 and the exhaust passage 116. The supercharger 120 increases the air loading of outside air drawn into the intake passage 114 to provide greater charge density during combustion to increase power output and / or efficiency of engine operation. In one embodiment, the supercharger 120 may include a compressor (not shown) driven at least in part by a turbine (not shown). The supercharger 120 may include multiple turbine and / or compressor stages.

[0017] The engine has a crankcase 160. The crankcase 160 encloses a (in Fig. 1 not shown) crankshaft, which is connected to (in Fig. 1) is connected to the engine's cylinders (not shown). The crankshaft may be lubricated with engine oil pumped by an oil pump (not shown) and sprayed onto the crankcase. The crankcase 160 may include a ventilation system. For example, unburned fuel, air, and exhaust gases may escape past the cylinders into the crankcase. The unburned fuel, air, and exhaust gases, as well as engine oil, may be drained by the crankcase ventilation system 160 and directed to a separator 180. The separator 180 may be configured to separate engine oil from the unburned fuel, air, and exhaust gases and to return the engine oil to the crankcase 160. The unburned fuel, air, and exhaust gases may be directed from the separator 180 to a muffler 122 disposed between the supercharger turbine and the exhaust conduit 116. The silencer 122 may be designed to dampen exhaust noise.In one embodiment, the muffler 122 may include an eductor (not shown). The eductor may create suction from the crankcase 160 through the settler 180 and into the muffler 122. For example, the eductor may utilize the Venturi effect to create suction as exhaust gases flow through the muffler 122.

[0018] In some embodiments, vehicle system 100 may further include an exhaust treatment system (not shown) connected in the exhaust conduit upstream and downstream of turbocharger 120. In one embodiment, the exhaust treatment system may include a diesel oxidation catalyst (DOC) and a diesel particulate filter (DPF). In other embodiments, the exhaust treatment system may additionally or alternatively include one or more emission control devices. Such emission control devices may include a selective catalytic reduction (SCR) catalyst, a three-way catalyst, a NOx trap, or various other devices or systems.

[0019] The vehicle 106 further includes a controller 130 for controlling various components related to the vehicle system 100. In one example, the controller 130 includes a computer control system. In one embodiment, the computer control system includes a processor, such as processor 132. The controller 130 may include multiple engine control units (ECUs), and the control system may be distributed among the individual ECUs. The controller 130 further includes computer-readable storage media, such as memory 134, containing instructions to enable on-board monitoring and control of the operation of the rail vehicle. The memory 134 may include volatile and non-volatile random access memory.

[0020] The controller may direct the command and control of the vehicle system 100. The controller may receive signals from various engine sensors 150 to detect operating parameters and operating conditions and adjust various engine actuators 152 accordingly to control the operation of the rail vehicle 106. For example, the controller may receive signals from various engine sensors, including, but not limited to, engine speed, engine load, boost pressure, exhaust pressure, ambient pressure, exhaust temperature, etc. As another example, the controller may receive a signal from a crankcase pressure sensor 170 indicative of a pressure of the crankcase 160. As another example, the controller may receive a signal from a crankshaft position sensor 172 indicative of a position of the crankshaft.Accordingly, the controller may control the vehicle system by sending commands to various components, such as drive motors, alternators, cylinder valves, throttle bodies, etc. Signals from engine sensors 150, 170, and 172 may 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.

[0021] The control device may include electronic on-board diagnostics to record engine operating parameters. Operating parameters may include, for example, measurements from sensors 150, 170, and 172. In one embodiment, the operating parameters may be stored in a database in memory 134. In one embodiment, current operating parameters may be compared with historical operating parameters to determine the trend in engine performance.

[0022] The control device may include electronic on-board diagnostics to identify and record potential deterioration and failure of components in vehicle system 100. For example, if a potentially non-functional component is identified, a diagnostic code may be stored in memory 134. In one embodiment, each type of deterioration identified by the control device may correspond to a unique diagnostic code. For example, a first diagnostic code may indicate wear of a piston ring of cylinder 1, a second diagnostic code may indicate wear of the piston ring of cylinder 2, a third diagnostic code may indicate potential deterioration of the crankcase ventilation system, etc.

[0023] The controller may further be connected to a display 140, 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 142 by sending a command to adjust various actuators 152 of the engine accordingly. Non-limiting examples of user input controls 142 may include a throttle control, a brake control, a keypad, and a power switch. Furthermore, engine operating characteristics, such as diagnostic codes corresponding to components no longer fully functional, may be reported to an operator and / or a maintenance team via a display 140.

[0024] The vehicle system may include a communications system 144 connected to the controller. In one embodiment, the communications system 144 may include a radio and an antenna to send and receive voice and data messages. For example, data may be exchanged between a 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 engine operating characteristics to the interlocking station via a message sent from the communications system 144.In one embodiment, a message may be sent from the communication system 144 to the interlocking station when a component of the engine that is no longer fully functional has been detected, and maintenance may be scheduled for the vehicle system.

[0025] An example of a component that is no longer fully functional could be an engine cylinder. During engine operation, the cylinder may become inoperable and allow unburned fuel and exhaust gases from around or around the piston to escape into the crankcase as blowby. Fig. 2 shows an embodiment of a cylinder 210 of the engine with blowby around a piston 230 during a compression stroke. The cylinder 210 has a cylinder wall 220 and a volume for injecting a mixture of fuel and air to be combusted. The piston 230 reciprocates within the cylinder 210 from a top dead center position to a bottom dead center position. The top dead center position corresponds to the position of the piston 230 closest to an intake valve 212 and an exhaust valve 216. The bottom dead center position corresponds to the position of the piston 230 farthest from an intake valve 212 and an exhaust valve 216. In one embodiment, the intake valve 212 may be opened to allow a mixture of fuel and air from the intake passage 214 into the cylinder 210. The exhaust valve 216 may be opened to allow combustion byproducts to exit the cylinder 210 through the exhaust line 218.The piston 230 may be connected to a crankshaft 250 via a connecting rod 240 so that the reciprocating motion of the piston 230 can be translated into a rotational motion of the crankshaft 250. The crankshaft 250 and the connecting rod 240 are enclosed in the crankcase 160. The piston 230 may have a plurality of grooves, each groove configured to hold a piston ring, such as piston rings 231, 232, and 233. Each piston ring 231, 232, and 233 may be configured to fit between the piston 230 and the cylinder wall 220 to seal the gap between the cylinder wall 220 and the piston 230.

[0026] In one embodiment, the engine may be a four-stroke engine having intake, compression, power, and exhaust strokes. During the intake stroke, a mixture of fuel and air may be drawn into cylinder 210 from intake passage 214 by opening intake valve 212. In one embodiment, fuel may be injected directly into cylinder 210 by a fuel injector installed in cylinder 210. Piston 230 generally moves away from top dead center during the intake stroke. During the compression stroke, intake valve 212 may be closed, and the mixture of fuel and air in cylinder 210 is compressed by the movement of piston 230 toward top dead center. During the power stroke, the mixture of fuel and air combusts, and piston 230 is driven away from top dead center by pressure in cylinder 210.In one embodiment, the fuel-air mixture may ignite spontaneously due to compression. In an alternative embodiment, the fuel-air mixture may be ignited by a spark from a spark plug. During the exhaust stroke, exhaust valve 216 is opened, and exhaust gases may be directed out of cylinder 210 through exhaust passage 218. Piston 230 generally moves toward top dead center during the exhaust stroke. In this way, the engine, e.g., crankshaft 250, may rotate twice during a four-stroke cycle.

[0027] In an alternative embodiment, the engine may be a two-stroke engine. In a two-stroke engine, the intake and exhaust functions partially overlap as the piston approaches bottom dead center at the end of the power stroke and as the piston moves away from bottom dead center at the beginning of the compression stroke. The compression stroke compresses the fuel and air mixture in the cylinder as the piston moves toward top dead center. During the power stroke, the fuel is ignited and the piston moves away from top dead center. This allows the engine, for example, the 250-degree crankshaft, to rotate once during a four-stroke cycle.

[0028] Furthermore, the engine may have a plurality of cylinders that fire in a predetermined order, 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 1-3-4-2 firing order, 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, e.g., the frequency of crankshaft revolutions 250, may be described as the first engine order. The firing frequency of a particular cylinder of a four-stroke engine may be described as half the engine order, where half the engine order is half the frequency of crankshaft revolutions 250.

[0029] As another example of a four-stroke engine, a twelve-cylinder engine might have a firing order of 1-7-5-11-3-9-6-12-2-8-4-10, where each cylinder fires exactly once every 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.

[0030] As another example of a two-stroke engine, a twelve-cylinder engine might 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 particular cylinder is the engine revolution frequency, and the firing frequency of all cylinders is twelve times the engine revolution frequency.

[0031] Fig. 2 shows an embodiment of a cylinder 210 of a four-stroke engine during a compression stroke. Blowby is represented by arrows 260 and 262. Blowby may be generated by the fuel and air mixture escaping from inside the cylinder 210 around the piston 230 and into the crankcase 160. The amount of blowby may be determined by a condition of the engine and the pressure differential between the cylinder 210 and the crankcase 160. The condition of the engine may include a condition of the cylinder wall 220 and / or the piston 230 and / or the piston rings 231, 232, and 233.

[0032] For example, the cylinder wall 220 may deteriorate as the engine is used. The cylinder wall 220 may develop scratches, gouges, nicks, and / or scuffs, increasing the gap between the piston 230 and the cylinder wall 220 and reducing the obstruction to gas flowing from, for example, the cylinder 210 to the crankcase 160. Thus, blowby may be increased in a cylinder that is no longer fully functional. In another example, the piston 230 and / or one or more of the piston rings 231, 232, and 233 may deteriorate as the engine is used. For example, the grooves in the piston 230 in which one or more of the piston rings 231, 232, and 233 may sit may become larger, possibly causing one or more of the piston rings 231, 232, and 233 to flutter or become loose, which may increase blowby. As a further example,For example, one or more of the piston rings 231, 232, and 233 may twist, crack, or become damaged in a manner that increases blowby. Thus, blowby may increase if one or more of the cylinders 210 and engine cylinder-related components degrade, where the engine cylinder-related components may include at least a piston 230, piston grooves, and piston rings 231, 232, and 233.

[0033] Furthermore, blowby may be increased as the pressure differential between cylinder 210 and crankcase 160 increases. In one example, the peak pressure differential during the compression stroke may be smaller than the peak pressure differential during the power stroke. During the compression stroke, the pressure in cylinder 210 may be determined by the pressure of the fuel and air mixture entering cylinder 210 and the reduction in volume of cylinder 210 during compression. During the power stroke, the compressed fuel and air mixture is ignited, further increasing the pressure in cylinder 210. Fig. Figure 3 shows an embodiment of cylinder 210 of the engine with blowby during the power stroke. Blowby during the power stroke may be greater than blowby during the compression stroke. The increased blowby during the power stroke is represented by arrows 310 and 312.

[0034] Blowby may be an engine condition that affects crankcase pressure 160. Other examples of engine conditions that may affect crankcase pressure 160 include one or more of the following: engine speed, engine load, crankcase temperature, crankcase ventilation flow, and a condition of the supercharger 120. As indicated by the data from Fig. 4, the crankcase pressure (CCP) 420 may change over time. In one embodiment, the crankcase pressure 420 may be a partial vacuum. For example, the data from Fig. 4, that the crankcase pressure 420 may vary in a range from about minus 6.5 to about minus 3.5 inches of water (In-H2O) at a nearly constant engine speed of about 1050 revolutions per minute (rpm), e.g., 17.5 Hz. Gases flowing past the piston 230 may have a pressure different than the crankcase pressure 420 and may thus contribute to transient fluctuations in the crankcase pressure 420. For example, exhaust gases flowing past the piston 230 during the power stroke may have a pressure higher than the crankcase pressure 420, and thus the exhaust gases may cause a transient increase in the crankcase pressure 420. Furthermore, the exhaust gases flowing past the piston 230 during the power stroke may have a higher pressure than unburned fuel and air flowing past the piston 230 during the compression stroke.Thus, blowby during the power stroke can cause a greater increase in crankcase pressure than blowby during the compression stroke. In other words, crankcase pressure 420 can have a frequency component at the power stroke frequency. In a four-stroke engine, the power stroke frequency component is half the engine revolution frequency. In a two-stroke engine, the power stroke frequency component is the engine revolution frequency.

[0035] Crankcase pressure 420 may be reduced by venting unburned fuel, air, and exhaust gases from the crankcase ventilation system 160 to a settler 180. In one embodiment, the venting may be enhanced by suction from an ejector or muffler 122. The ejector may utilize the Venturi effect to create suction as exhaust gases flow through muffler 122, and therefore, the suction may vary with the exhaust flow through muffler 122. Crankcase pressure 420 may fluctuate around an average crankcase pressure at a given engine speed, as shown in the data from Fig. 4. For example, the average crankcase pressure of Fig. 4 about minus 5.0 In-H2 O. Fig. Figure 4 shows an example graph of time-domain crankcase pressure data. The time-domain crankcase pressure data can be retrieved and transformed into a frequency-domain pressure signal.

[0036] One solution for diagnosing an engine condition is monitoring the average or equilibrium crankcase pressure. For example, a potential faulty engine condition can be detected when the average crankcase pressure exceeds an absolute pressure threshold. However, an increase in average crankcase pressure can be caused by a number of different degraded components, and it can be time-consuming for a maintenance team to determine the source of the degraded component during engine maintenance.

[0037] An engine condition may be diagnosed based on the frequency content of the crankcase pressure. A suitable example of crankcase pressure frequency content may be obtained as follows: the crankcase pressure may be measured to generate a time-domain crankcase pressure signal; and the time-domain crankcase pressure signal may be retrieved and transformed to generate a frequency-domain crankcase pressure signal. The frequency-domain crankcase pressure signal may include a set of frequency components with different frequencies and magnitudes. The frequency content of the crankcase pressure is the relative magnitude of the frequency components of the frequency-domain crankcase pressure signal and / or is the measured frequency content generated using a bandpass filter. Pressure measurements may be performed using a suitable pressure sensor, for example, crankcase pressure sensor 170.A discrete Fourier transform, such as a fast Fourier transform, can be used to generate the frequency-domain crankcase pressure signal. Furthermore, the condition of the engine can be diagnosed based on the frequency content of the crankcase pressure.

[0038] Fig. Figure 5 shows data from a frequency-domain crankcase pressure signal of an engine capable of operating at a healthy crankcase pressure. For example, the engine may be a four-stroke engine operating at 1050 rpm. Thus, the first engine order is 17.5 Hz, and the half engine order is 8.75 Hz. The crankcase pressure may vary at a periodic frequency as the crankshaft 250 rotates within the crankcase 160. For example, the frequency content of the crankcase pressure may include a peak pressure 510 at the first engine order frequency. In other words, the largest value of the frequency content may occur at the first-order frequency component. The first-order frequency component may be due to local piston motion within the cylinder. For example, during one crankshaft revolution, the piston moves from top dead center to bottom dead center and back to top dead center.Thus, the piston's movement can generate a pressure wave in the crankcase at the frequency of the crankshaft rotation. The first-order frequency component can dominate the crankcase pressure signal due to the local piston dynamics at the sensor.

[0039] The crankcase pressure may also contain frequency content at other harmonics of the first-order frequency, for example, at a second-order frequency (twice the engine frequency), at a third-order frequency (three times the engine frequency), etc. Likewise, the crankcase pressure may contain frequency content at frequencies lower than the first-order frequency, for example, at a half-order frequency (half the engine frequency). Fig. Figure 5 shows an example of a half-order component, 520, and shows a data graph of a frequency-domain crankcase pressure signal from an engine capable of operating at a healthy crankcase pressure. The graph represents pressure magnitudes at discrete frequencies.

[0040] A healthy engine may have an average crankcase pressure below a threshold pressure. Further, a healthy engine may have a frequency content substantially located around the half-order frequency, for example, frequency range 550. In one embodiment, frequency range 550 may be plus or minus ten percent of the half-order frequency, depending on the engine speed. Frequency content near the half-order frequency may be caused by at least a healthy amount of blowby from piston 230. In a healthy engine, the frequency content may have frequency components substantially located near the half-order frequency with magnitudes below a threshold, for example, threshold 560. An engine may degrade if one or more components of the engine are no longer fully functional.For example, the non-functional components can cause the engine to operate less efficiently, produce less power, and / or emit more pollutants. Furthermore, the condition of the non-functional components can accelerate component deterioration, which can increase the likelihood of catastrophic engine failure and track failure.

[0041] A cylinder that is no longer fully functional is an example of a no longer fully functional engine component. The blowby in a cylinder that is no longer fully functional is increased compared to a healthy cylinder. Increased blowby can create a transient upward pressure excursion as the high-pressure gases from cylinder 210 escape into crankcase 160. The transient pressure excursion can occur at the frequency at which the cylinder that is no longer fully functional fires. For example, in a four-stroke engine, the transient pressure excursion can occur at the half-order frequency. In a two-stroke engine, the transient pressure excursion can occur at the first-order frequency. Thus, it may be desirable to capture the frequency content of the crankcase pressure substantially close to the half-order frequency, 520, for example, in the 550 frequency range.

[0042] The frequency content near the half-order frequency may, for example, be caused by different amounts of blowby escaping from each of the cylinders of a multi-cylinder engine. The differences may, for example, be caused by different wear patterns or manufacturing differences of each cylinder. Thus, the frequency content in a healthy engine may have frequency components that are substantially close to the half-order frequency, with magnitudes that are below a threshold, for example, threshold 560. However, a cylinder that is no longer fully functional may have increased blowby, and the frequency content of a four-stroke engine with the cylinder that is no longer fully functional may have frequency components substantially close to the half-order frequency, with magnitudes that are above threshold 560. For example, Fig. 6 Data that may indicate a cylinder that is no longer fully functional, where the half-order component, 620, exceeds the threshold 560, and the data shows a frequency-domain crankcase pressure signal of the engine, which may be operating at a crankcase pressure that may indicate a certain type of cylinder functional deterioration. For example, the engine may be Fig. 6 have a component that is no longer fully functional and is causing blowby, such as worn piston rings. The diagnosis can then include both a warning about the deterioration in function and an indication of the type and / or location of the engine component that is no longer fully functional.

[0043] Thus, in one embodiment, a no longer fully functional cylinder of a four-stroke engine may be detected 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 the frequency range 550, and a no longer fully functional cylinder of a four-stroke engine may be detected based on the integration being greater than an integral threshold.

[0044] 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 may 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 motor or another motor component that is no longer fully functional can be identified and reported by the control device.

[0045] Another example of a malfunctioning engine component is a malfunctioning crankcase ventilation system. For example, the malfunctioning crankcase ventilation system may not vent gases from the crankcase 160 at a sufficiently high rate, which may cause the average or peak crankcase pressure to exceed an average crankcase pressure threshold. The malfunctioning crankcase ventilation system may affect all cylinders of a multi-cylinder engine in a similar manner; therefore, the half-order frequency components may not be significantly affected by the malfunctioning crankcase ventilation system.In one embodiment, a potentially malfunctioning crankcase ventilation system may be diagnosed by detecting that the average crankcase pressure exceeds the average crankcase pressure threshold and the frequency content of the crankcase pressure has a half-order frequency component that is less than a half-order threshold. Both the average crankcase pressure and the half-order thresholds may be based on, for example, one or more of the following: engine speed, engine load, crankcase temperature, and historical engine data.

[0046] Another example of a malfunctioning engine component is a malfunctioning supercharger, such as supercharger 120. In one embodiment, supercharger 120 may have a seal lubricated by engine oil draining into crankcase 160. For example, a malfunctioning supercharger seal may provide a path for high-pressure charge air and / or exhaust gas from supercharger 120 to enter crankcase 160. The malfunctioning supercharger may affect all cylinders of a multi-cylinder engine in a similar manner; therefore, the half-order frequency components may not be significantly affected by the malfunctioning supercharger.In one embodiment, a potentially inoperable charger may be diagnosed by detecting that an average crankcase pressure exceeds an average crankcase pressure threshold and the frequency content of the crankcase pressure has a half-order frequency component that is less than a half-order threshold.

[0047] Another example of a failing engine component is a failing crankcase. For example, a healthy engine may have a crankcase that forms an essentially closed system. If the crankcase is essentially closed, the movement of the piston in the crankcase may cause a pressure wave at the frequency of the engine rotation, e.g., at a first-order frequency. However, a failing crankcase may have a crankcase cap that was forced open during operation, or a crankcase cap that was improperly replaced or sealed during routine maintenance, etc.When the crankcase is no longer fully functional, the crankcase may be open to ambient air, increasing the average crankcase pressure and affecting the dynamics of the pressure wave within the crankcase at the frequency of the crankshaft rotation. As an example, the average crankcase pressure may increase within 0.5 IN-H2O atmospheric pressure, and the first-order frequency response of the crankcase pressure signal may be significantly reduced when the crankcase is no longer fully functional. The crankcase inoperability may affect all cylinders of a multi-cylinder engine in a similar manner, so the half-order frequency components may not be significantly affected by the crankcase inoperability.In one embodiment, a potentially inoperable crankcase may be diagnosed by detecting that an average crankcase pressure exceeds an average crankcase pressure threshold and the frequency content of the crankcase pressure has a half-order frequency component that is less than a half-order threshold. In one embodiment, a potentially inoperable crankcase may be diagnosed by detecting that an average crankcase pressure exceeds an average crankcase pressure threshold and the frequency content of the crankcase pressure has a half-order frequency component that is less than a half-order threshold.

[0048] The above examples demonstrate different methods for distinguishing between different types of engine degradation based on the frequency content of the crankcase pressure during engine operation.

[0049] The crankcase pressure may be monitored during engine operation, as with an embodiment of a method in Fig. 7 is shown. Fig. 7 shows an embodiment of a method 700 for diagnosing a condition of the engine. In one example, method 700 may include diagnosing a condition of the engine based on a frequency content of the crankcase pressure. In another example, method 700 may include distinguishing between different types of degradations based on a frequency content of multiple frequencies of the crankcase pressure.

[0050] For example, considering both frequency content and equilibrium crankcase pressure can provide information that distinguishes between the deterioration of a specific cylinder and normal wear affecting all engine cylinders to the same extent.In this example, an elevated equilibrium pressure value above an equilibrium threshold, but with the magnitude of the frequency content of the crankcase pressure substantially near half-order frequency 520 being below threshold 560, may indicate wear of all cylinders, while an elevated equilibrium pressure value above the equilibrium threshold, but with the magnitude of the frequency content of the crankcase pressure substantially near half-order frequency 520 being above threshold 560, may indicate that one of the cylinders is experiencing increased degradation relative to the other cylinders of the engine.

[0051] As another example, the frequency content and the equilibrium crankcase pressure can provide information that distinguishes between increased blowby of a particular cylinder and a reduced ventilation rate of the crankcase ventilation system.In this example, an elevated equilibrium pressure value above an equilibrium vent threshold, but where the magnitude of the frequency content of the crankcase pressure substantially near half-order frequency 520 is below threshold 560, may indicate degradation of the crankcase ventilation system, while an elevated equilibrium pressure value above the equilibrium vent threshold, but where the magnitude of the frequency content of the crankcase pressure substantially near half-order frequency 520 is above threshold 560, may indicate that one of the cylinders is experiencing increased degradation relative to the other cylinders of the engine.

[0052] At 710, the crankcase pressure is measured. For example, the pressure of the crankcase 160 may be measured with a sensor, such as a crankcase pressure sensor 170, to generate a time-domain crankcase pressure signal.

[0053] At 720, the crankcase pressure may be filtered. In one embodiment, the time-domain crankcase pressure signal 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.

[0054] At 730, the crankcase pressure may be sampled. For example, the crankcase pressure may be sampled at a frequency at least as high as the Nyquist rate. In one embodiment, the time-domain crankcase pressure signal may be sampled at a frequency higher than twice the first engine order frequency. In one embodiment, the time-domain crankcase pressure signal may be sampled at a frequency twice the engine frequency that exceeds a red line. Thus, by low-pass filtering and sampling at a frequency at least as high as the Nyquist rate, the frequency content of the generator data may not be corrupted.

[0055] At 740, the crankcase pressure may be transformed. For example, the sampled crankcase pressure may be transformed to generate a frequency-domain crankcase pressure signal. In one embodiment, a fast Fourier transform may be used to generate the frequency-domain crankcase pressure signal.

[0056] At 750, a correlation algorithm may be applied. In one embodiment, a correlation algorithm may be applied to compare the frequency-domain crankcase pressure signal, e.g., the frequency content of the crankcase pressure, 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 historical engine data.

[0057] For example, historical engine 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 half-order engine 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 half-order engine component for a given engine speed and load may indicate that the supercharger or crankcase ventilation system is losing functionality.

[0058] At 760, it is determined whether a potential fault has been found. Potential faults may include, for example, a cylinder that is no longer fully functional, a supercharger that is no longer fully functional, or a crankcase ventilation system that is no longer fully functional. In one embodiment, the potential fault may be found by applying the correlation algorithm of 750. If a potential fault is found, method 700 proceeds to 780, and diagnosis of the engine may continue. If no potential fault is found, method 700 proceeds to 770.

[0059] At 770, crankcase pressure data may be recorded. In one embodiment, the frequency content of the crankcase pressure data may be stored in a database containing engine history data. For example, the database may be stored in memory 134 of controller 130. As another example, the database may be stored at a location other than on rail vehicle 106. For example, engine history data may be encapsulated in a message and sent using a communication system 144. In this way, a control center may monitor the health of the engine in real time. For example, the control center may perform steps, such as steps 740, 750, 760, 770, and 780, to diagnose the condition of the engine using the engine data sent using communication system 144.For example, the interlock may receive engine data, including crankcase pressure data, from the rail vehicle 106, transform the crankcase pressure data to frequency, apply a correlation algorithm to the transformed data, and diagnose potential engine degradation. Furthermore, the interlock may schedule maintenance and deploy serviceable locomotives and maintenance crews in a manner that optimizes capital expenditure. Historical engine data may also be used to evaluate engine health before and after engine service, engine modifications, and engine component replacement. Method 700 may end after 770.

[0060] At 780, a potential fault may be reported. In one embodiment, a potential fault may be reported to the locomotive operating team via display 140. 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 control center using communication system 144. Further, the severity of the potential fault may be reported. For example, diagnosing a fault based on the frequency content of the crankcase pressure may enable earlier fault detection than diagnosing the fault using only the average crankcase pressure. 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 value and the magnitude of one or more components of the frequency content of the crankcase pressure.

[0061] If the crankcase pressure indicates a potentially faulty component of the engine, further diagnostics may be performed, as with an embodiment of a method in Fig. 8. By analyzing the frequency content of the crankcase pressure, 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 can be adjusted to potentially reduce additional functional deterioration of the engine component and to reduce the likelihood of additional engine failure and failure during operation. At 800 and as in Fig. 8, the potential error can be further diagnosed. Fig. 8 shows an embodiment of a method 800 for diagnosing a condition of the engine.

[0062] At 805, 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 may be a de-energized cylinder in one embodiment, and method 800 continues to 820, where the de-energized cylinder may be identified. However, if the magnitude of the half-order component is not greater than the half-order threshold, the potential fault may be a de-energized supercharger 120 or a de-energized crankcase ventilation system, and method 800 continues to 810.

[0063] At 810, the potential fault may be reported as a degraded supercharger 120 or a degraded crankcase ventilation system. In one embodiment, the potential fault may be reported to the locomotive operator team via display 140, and the operator may adjust the operation of the rail vehicle 106 to reduce the risk of further degradation. In one embodiment, a message diagnosing the potential fault as a degraded supercharger 120 or a degraded crankcase ventilation system may be sent to a signaling center using communication system 144. Method 800 may end after 810.

[0064] At 820, a per-cylinder diagnostic may be performed to identify the inoperative cylinder. In one embodiment, time-domain measurements may be used to identify the inoperative cylinder. For example, crankcase pressure may exhibit periodic spikes, and the spikes may be correlated with one or more of the following: crankshaft position, camshaft position, or fuel injection sequence. Thus, in one embodiment, the inoperative cylinder may be identified by correlating time-domain crankcase pressure information with one of the following: crankshaft position, camshaft position, or fuel injection sequence. In another example, the inoperative cylinder may be identified by correlating time-domain crankcase pressure information with the engine's firing order.Furthermore, a correlation algorithm can compensate for a pressure wave transport delay between the no longer fully functional cylinder and the pressure sensor.

[0065] Blowby from a non-functional cylinder can affect other engine operating conditions. For example, the crankcase temperature may peak during the power stroke of the non-functional cylinder. Likewise, the temperature and pressure of vent gases from the crankcase ventilation system may spike or pulsate in a manner that can be correlated with the non-functional cylinder.

[0066] 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 the average crankcase pressure and / or the frequency content of the crankcase pressure. For example, fuel injection to one cylinder may be disabled 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.

[0067] In one example, the half-order frequency component of crankcase pressure may be monitored for each disabled cylinder of a four-stroke engine. The disabled cylinder may be a non-functional cylinder if the half-order frequency component falls below a half-order threshold while the cylinder is disabled. The disabled cylinder may be a fully functional cylinder if the half-order frequency component remains above a half-order threshold while the cylinder is disabled. In other words, the non-functional 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 diagnostic provided by selective override may be performed when the engine is idling or only lightly loaded.

[0068] Likewise, the average crankcase pressure can be monitored while fuel injection to one or more engine cylinders is selectively disabled. For example, the average crankcase pressure may drop disproportionately if the no longer fully functional cylinder is disabled.

[0069] In one embodiment, the selective override diagnosis may further be based on the frequency content of other engine operating parameters, such as crankcase ventilation flow, crankcase ventilation temperature, or crankcase temperature. For example, the crankcase ventilation flow 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.

[0070] In one embodiment, the inoperative cylinder may be detected 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 crankcase pressure. 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 undergoes diagnostics.

[0071] In one embodiment, the inoperative cylinder may be identified by changing the fuel injection timing. For example, advance angle adjustments may be used to diagnose the inoperative cylinder. For example, the fuel injection timing may be retarded to potentially increase blowby and the frequency content of the half-order frequency component. By retarding the timing, combustion and exhaust temperatures may rise, thereby increasing the speed of the supercharger 120 and the pressure of the air in a manifold. Thus, peak firing pressure in the cylinders may be increased, and blowby may be increased.

[0072] At 825, it is determined whether the inoperable cylinder has been identified. If the inoperable cylinder has been identified, method 800 may continue at 840. If the inoperable cylinder has not been identified, method 800 may continue at 830. At 830, it may be reported that the potential fault affects an unknown cylinder. The report may be provided, for example, via a display 140 or a message sent using communication system 144.

[0073] At 840, the identity of the potentially no longer fully functional cylinder can be reported. The report can be made, for example, via a display 140 or a message sent via the communication system 144.

[0074] At 845, the severity of the potential fault may be compared to a threshold. For example, it may be more preferable to shut down the engine than to allow a no longer fully 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 fault is severe. For example, the potential fault may be classified as severe if a magnitude of the half-order frequency component exceeds a threshold. The engine may be stopped at 850 if the severity of the potential fault exceeds the threshold. Otherwise, method 800 may continue at 860.

[0075] At 860, a request to schedule a workshop inspection may be sent, for example, through a message sent via the communication system 144. Furthermore, by sending the potential fault condition and the severity of the potential fault, the time the rail vehicle 106 is out of service may be shortened. 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 shortened by reducing the engine's power, for example, by adjusting an engine operating parameter based on the diagnosed condition.

[0076] At 865, a determination may be made as to whether engine derating is permitted. For example, derating engine power may reduce blowby, which may reduce the equilibrium crankcase pressure and the magnitude of one or more components of the crankcase pressure frequency content. If derating is not permitted, method 800 may end. However, if engine derating is permitted, method 800 may continue to 870.

[0077] At 870, an engine operating parameter may be adjusted, for example, to reduce additional degradation of the inoperable component. In one embodiment, engine speed or power may be controlled to reduce blowby of all cylinders. In one embodiment, fuel injection to the potentially inoperable cylinder may be reduced or disabled while operation of the other cylinders continues. Thus, the engine may continue to operate, and blowby of the inoperable cylinder may be reduced. In this way, the engine may be adjusted to potentially reduce additional degradation of the engine component and to reduce the likelihood of catastrophic engine failure and track failure.

[0078] In one embodiment, a test kit may be used to reduce a frequency content of the crankcase pressure and diagnose a condition of the engine based on the frequency content of the crankcase pressure. For example, a test kit may include a controller operable to communicate with one or more crankcase pressure sensors coupled to a crankcase and operable to sense crankcase pressure. The controller may further operate to transform signals from the one or more crankcase pressure sensors into a frequency content representative of crankcase pressure frequency information. The controller may further operate to diagnose a condition of the engine based on the frequency content of the crankcase pressure.

[0079] 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. Terms of approximation, 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 terms of approximation 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.

[0080] 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 an ability, capability, 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".

[0081] The embodiments described herein are examples of articles, systems, and methods that include elements corresponding to the elements of the invention recited in the clauses. The description may enable one of ordinary skill in the art to make and use embodiments having alternative elements that also correspond to the elements of the invention recited in the clauses. The scope of the invention thus includes articles, systems, and methods that do not differ from the language of the clauses and further includes other articles, systems, and methods that differ only insignificantly from the language of the clauses. Although only certain features and embodiments are shown and described herein, many modifications and changes may be obvious to one of ordinary skill in the art. The appended clauses cover all such modifications and changes.

Claims

[1] A method for an engine having a crankcase, comprising: - Diagnosing, by means of a control device, a condition of the engine based on a frequency content of a measured crankcase pressure, wherein the diagnosing of the engine condition includes determining whether there is a deterioration in the function of an engine cylinder and a component related to the engine cylinder, said component being a turbocharger; the method further comprising: - adjusting an engine operating parameter by means of the control device based on the diagnosed condition; and - further correlating crankcase pressure information with one of the following: crankshaft position, camshaft position, fuel injection sequence. [2] The method of claim 1, wherein diagnosing the engine condition includes determining a condition that blowby from a degraded engine cylinder and / or a component related to a degraded engine cylinder is present, and the condition is based at least in part on a power stroke frequency component of the frequency content of the crankcase pressure exceeding a power stroke frequency component threshold. [3] The method of claim 2, wherein the engine is a four-stroke engine and the power stroke frequency is approximately half the crankshaft rotation frequency, and diagnosing the engine condition includes determining that the magnitude of the power stroke frequency component is greater than a power stroke frequency component threshold. [4] The method of claim 1, further comprising reducing engine power in response to detecting degradation of the engine cylinder or the component related to the engine cylinder. [5] The method of claim 1, further comprising reducing an amount of fuel injected into the inoperative engine cylinder in response to an affirmative determination of degradation of the engine cylinder. [6] The method of claim 1, further comprising: - the determination of a power swing frequency component of the frequency content; and - selectively overriding fuel injection into one or more cylinders of the engine based at least in part on the power stroke frequency component. [7] The method of claim 2, further comprising: - Changing the engine fuel injection in an engine cylinder; and - Observe whether there is a change in the frequency content caused by the change in fuel injection. [8] The method of claim 2, wherein the engine is a two-stroke engine and the power stroke frequency is approximately the crankshaft rotation frequency, and diagnosing the engine condition includes determining that the magnitude of the power stroke frequency component is greater than a power stroke frequency component threshold. [9] The method of claim 1, further comprising: - Measuring an average crankcase pressure; - comparing the measured average crankcase pressure with a first average crankcase pressure threshold; - determining a first-order frequency component of the frequency content, the first-order frequency approximately corresponding to a crankshaft rotation frequency; comparing the magnitude of the first-order frequency component with a threshold value for the first-order frequency; and - determining the degradation of the crankcase function based at least in part on whether the measured average crankcase pressure exceeds the first average crankcase pressure threshold and whether the magnitude of the first order frequency component is less than the first order frequency threshold. [10] The method of claim 1, further comprising: - Measuring an average crankcase pressure, the engine being a four-stroke engine; - comparing the measured average crankcase pressure with a threshold value for the average crankcase pressure; - determining a degradation of a charger and / or a crankcase ventilation system based at least in part on whether the measured average crankcase pressure exceeds the average crankcase pressure threshold; and - Determining whether the frequency content of the crankcase pressure has a half-order frequency component that is less than a half-order frequency component threshold, where the half-order frequency is approximately half of a crankshaft rotation frequency. [11] A method for an engine having a crankcase enclosing a crankshaft, comprising: - distinguishing, by means of a controller, between different types of degradation in the form of engine degradation and turbocharger degradation based on an average crankcase pressure and a frequency content of a measured crankcase pressure; wherein the engine is a four-stroke engine and the frequency content includes a half-order component that is substantially half of the crankshaft revolution, the method further comprising distinguishing the type of degradation from a given set of degradation types based at least in part on an average crankcase pressure, the method further comprising: - comparing the average crankcase pressure with a first average crankcase pressure threshold; and - detecting a magnitude of the half-order component of the frequency content that is less than a second magnitude threshold; and - determining a deterioration in the performance of a turbocharger and / or a crankcase ventilation system based on the steps of comparing the average crankcase pressure and detecting the magnitude; and - Adjusting an engine operating parameter based on the step of distinguishing the functional deteriorations. [12] The method of claim 11, further comprising diagnosing a blowby condition of the engine in response to determining that a magnitude of the half-order component of the frequency content exceeds a certain magnitude threshold. [13] The method of claim 12, further comprising basing the first average crankcase pressure threshold and / or the second average crankcase pressure threshold on at least one of the following: engine speed, engine load, crankcase temperature, engine history data.

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