CROSS REFERENCE TO RELATED APPLICATIONS
- BACKGROUND OF THE INVENTION
1. Field of the Invention
This disclosure relates to the detection and response to unwanted fueling of an internal combustion engine arising from a lubricating oil leak associated with a pressure-lubricated air system component such as a turbocharger.
As used herein, the term “fugitive fueling” means a phenomenon in which an engine receives fuel in excess of that which a fuel controller intends to deliver, either by injectors or by other fuel delivery devices. Fugitive fueling may occur in a variety of situations. For example, if an engine is operated in a hydrocarbon contaminated atmosphere, such as could occur in the event of a spill at a petroleum transfer terminal or a recycling facility, sufficient unwanted or fugitive hydrocarbons may be inducted by the air intake system of an engine to cause overspeed and severe engine damage. A mishap such as a vehicular accident or train wreck may create a fugitive fueling situation, too.
Another type of fugitive fueling may occur due to a leak in an engine lubrication system. Such a leak may occur in a turbocharger or other component connected with the engine's air inlet system. Those skilled in the art will appreciate that engines, particularly diesel engines, are capable of operating quite well on lubricating oil, including lubricating oil aspirated into the engine's cylinders as a result of leaking turbocharger seals or failed turbocharger bearings.
- BRIEF DESCRIPTION OF THE INVENTION
A need exists for a system and method to detect and respond to fugitive fueling resulting from turbocharger or other pressure-lubricated component failure, whether the failure be in the form of leaking seals or worn or broken bearings, or yet other causes, so as to allow an engine to be stopped before damage occurs due to resultant fugitive fueling.
According to an aspect of the invention, a method for detecting fugitive fueling arising from a pressure-lubricated air inlet system component, such as a turbocharger, within an internal combustion engine having pressure-lubricated main bearings and a pressure-lubricated turbocharger includes monitoring lubricating oil pressure in at least one location within a lubrication circuit of the engine and comparing the monitored oil pressure with a failure range contained within a turbocharger failure template. If the monitored oil pressure lies within the failure range of the turbocharger failure template, remedial action is taken to mitigate engine damage caused by oil entering the engine's cylinders from a failed turbocharger.
According to another aspect of the present invention, the failure template contained within the controller preferably includes a software model for predicting lubricating oil pressure, including an acceptable range of variation exhibited by an engine having a properly operating turbocharger, with the model further including a failure range for the monitored oil pressure which indicates that the turbocharger has failed.
According to another aspect of the present invention, a system for detecting fugitive fueling arising from turbocharger failure within an internal combustion engine includes a pressure sensor for monitoring lubricating oil pressure within a lubrication circuit feeding oil to a turbocharger, and a controller for receiving the output of the pressure sensor and for comparing the sensor output with a turbocharger failure template, with the controller taking at least one step to mitigate engine damage from oil ingestion if the results of the comparison indicate that the turbocharger has failed. The controller may mitigate engine damage in several ways, such as by activating an air supply cutoff device, such as an air shutter in the air inlet system, or by activating a self-load device for the engine or by activating an inert gas supply device for furnishing inert gas to the engine's air inlet system.
It is an advantage of a method and system according to the present invention that fugitive fueling due to turbocharger failure may be detected rapidly, allowing time for an engine to be shut down before further engine damage occurs.
It is another advantage of a method and system according to the present invention that the system may be implemented at least in part with sensors commonly available in turbocharged engines.
BRIEF DESCRIPTION OF THE DRAWINGS
Other advantages, as well as features of the present invention will become apparent to readers of this specification.
FIG. 1 is a schematic representation of an engine having a turbocharger failure detection system according to an aspect of the present invention.
FIG. 2 is a block diagram of an engine and supporting componentry according to an aspect of the present invention.
FIG. 3 shows a portion of a lubrication system of an engine according to an aspect of the present invention.
FIG. 4 illustrates several plots related to engine oil pressure in a turbocharger failure episode.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 5 is a chart showing lubrication oil pressure monitoring and turbocharger failure detection according to an aspect of the present invention.
As shown in FIGS. 1 and 2, engine 10 has a crankshaft, 14, which as shown in FIG. 2 as being coupled to an alternator, 64. This configuration is commonly used with diesel-electric locomotives, as well as stationary power plants and diesel-electric open pit mining trucks and other vehicles. Engine 10 also includes exhaust manifold 18, which provides exhaust gas to exhaust turbine 26 of turbocharger 22. Exhaust gases leave turbocharger 22 by means of exhaust pipe 27.
Turbocharger 22 includes not only exhaust turbine 26, but also compressor section 30, which is coupled to exhaust turbine 26 on a common shaft (not shown) having various seals and bearings (not shown). The bearings and seals used in any particular turbocharger are selected by the turbocharger's designer; these details beyond the scope of this invention, it being understood that seals, bearings, and other internal parts of turbochargers are subject to wear and ultimately, to failure. And, failure of turbocharger seals and bearings is frequently accompanied by both the creation of a unique lubrication pressure signature and by aspiration of fugitive oil into the engine's air inlet system. Such oil frequently becomes fugitive fuel.
Engine 10 also includes intercooler 36, which furnishes air to engine air inlet 45. After traveling through engine air inlet 45, air enters intake manifold 40 and then goes into engine 10. If the seals or bearings of turbo 22 fail, oil will pass into intercooler 36 and then into engine air inlet 45. Ultimately, the oil will be drawn into the power cylinders of engine 10.
As shown in FIG. 1, engine 10 also includes air shutter 44, which is an emergency shut down device, as is tank 48, having a supply of inert gas which is admitted to intake 45. Valve 50 is controlled by controller 52 (FIG. 2). As shown specifically in FIG. 2, controller 52 operates fuel system 60 with the assistance of a number of sensors, 56. Controller 52 is also attached to a battery, 72, which is charged by alternator 64. Alternator 64 has a number of loads, 68, including a self-load which may be used to absorb power from engine 10 so as to correct overspeed situations which could otherwise result from fugitive fueling.
FIG. 3 illustrates additional detail about the lubrication system of engine 10. Oil reservoir 76 is equipped with a discharge/inlet line 80, which is connected with oil pump 84. Higher pressure oil leaving oil pump 84 passes into header 86, wherein the oil flows first through oil filter 88 and then through oil cooler 98. Oil then passes through line 90 and into main bearings 92 before passing into turbocharger 22. Turbocharger 22 is also serviced optionally by line 23, which is also shown in FIG. 1. Oil leaving turbocharger 22 passes through line 25 (FIG. 1) and back to sump 76.
As shown in FIG. 3, oil pressure may be measured by any of sensors S1, S2, S3, or S4. Sensor S1 measures oil pressure at a location adjacent oil pump 84. Sensor S2 measures oil pressure at a location within header 86 downstream of filter 88 and oil cooler 98. Oil pressure sensor S3 measures oil pressure in dedicated line 23 furnishing lubricating oil directly to turbocharger 22. Finally, oil pressure sensor S4 measures oil pressure directly within turbocharger 22. Each of sensors S1-S4 is connected with controller 52.
FIG. 4 illustrates various engine operating parameters accompanying an episode of turbocharger bearing failure. In effect, FIG. 4 illustrates a turbocharger failure template. The uppermost part of the plot of FIG. 4 is engine RPM, which remains fairly constant until the end of the time period depicted in the plot, at which point the engine's RPM accelerates to a destructive maximum due to uncontrolled fugitive fueling from a failed turbocharger. The middle plot of FIG. 4 illustrates predicted or modeled engine oil pressure compared with the actual pressure being monitored. The lowermost plot of FIG. 4 is the difference between the modeled and monitored oil pressures. Notice that the pressure difference first dithers about a common point, essentially zero difference, and then increases at a very steep rate due to turbocharger failure. At time t1, the modeled pressure and monitored pressure diverge. In other words, the monitored oil pressure enters a failure range in the turbocharger's failure template. An acceptable range of variation in actual oil pressure from the predicted pressure would be a small fraction of the variation shown in FIG. 4.
At time t2, engine 10 is being decelerated, and at time t3, engine 10 is accelerating in an uncontrolled state, propelled at least in part by fugitive fueling caused by oil leaking from a failed turbocharger. Notice that at time t3, engine speed increases rapidly, and the difference between the observed oil pressure and the predicted oil pressure also increases rapidly.
It may be seen from the foregoing that a window exists from time t1 to time t2 to take remedial action. This of course depends upon the monitoring of lubricating oil pressure depicted in FIG. 4.
FIG. 5 shows a monitoring and corrective action sequence intended to prevent the situation shown at times t2 and t3 of FIG. 4. Beginning at block 100, controller 52 begins monitoring lube oil pressure at block 104. Essentially, this monitoring of lubrication oil pressure will ideally be done whenever engine 10 is operating and, certainly, whenever engine 10 has reached a stabilized operating state, including engine temperature. Monitoring may be performed at a variety of locations within the lube oil system engine 10, including any of the sensors S1-S4; what is necessary is that a sensor be placed to detect failure of turbocharger 22 by detecting a signature fall-off in oil pressure. Monitoring may be performed at all operating modes, especially at idle. In this respect, the monitoring provided by the present system and method departs from many known monitoring systems which generally discard data taken during engine idle.
At block 108, the algorithm within controller 52 asks the question as to whether the oil pressure is within the failure range contained within the turbocharger failure template illustrated as extending between times t1 and t2 of FIG. 4. If the answer at block 108 is no, the routine continues again at block 104. If, however, the answer to the question at block 108 is yes, controller 52 will decide that the monitored oil pressure lies within the failure range of the turbocharger failure template, and mitigation of engine damage will begin at block 112. Such mitigation may take the form of employing or activating air supply cutoff device 44, or by stopping all intended fueling, or by injecting inert gas into the engine's air inlet system by opening valve 50 connected with gas supply 48, or by using load 68 to either stop the engine or maintain its speed in a controlled manner so as to avoid engine overspeeding and consequential damage. Having taken the mitigation steps at block 112, controller 52 ends the routine at block 116.
As noted above, lubricating oil pressure may be measured within a lubrication header downstream from a filter and oil cooler, but upstream from both the turbocharger and the main bearings. Alternatively, the oil pressure may be measured either adjacent the engine's lubricating oil pump or adjacent the turbocharger or, alternatively, within an oil pressure line serving only the turbocharger.
The present method and system may be employed with various pressure-lubricated air inlet system components in addition to the previously described turbocharger. For example, an air-to-oil intercooler leak may result in the ingestion of lubricating oil into an engine's cylinders, producing a response which will be very similar to that caused by a failed turbocharger. And, failures of other types of air system components which utilize or handle lubricating oil under pressure may result in fugitive fueling. Each of these components has a failure template including an oil pressure effect which is unique, and which offers an opportunity to monitor oil pressure as a method for detecting unique component failures. In one embodiment, the component failure template may be configured to indicate failure of a specific pressure-lubricated component when a pressure sensor, such as one of sensors S1-S4, or yet other sensors, indicates that oil pressure is decreasing at a rate in excess of a predetermined threshold.
The foregoing invention has been described in accordance with the relevant legal standards, thus the description is exemplary rather than limiting in nature. Variations and modifications to the disclosed embodiment may become apparent to those skilled in the art and fall within the scope of the invention. Accordingly the scope of legal protection afforded this invention can only be determined by studying the following claims.