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1. Field of the Invention
The subject matter disclosed herein relates to the use of specific exhaust temperature anomalies in multi-cylinder internal combustion engines to detect unwanted fugitive fueling.
2. Discussion of the Prior Art
As used herein, the term “fugitive fueling” means a phenomenon in which an engine receives fuel in excess of that which the engine's fuel controller intends to deliver, either by injectors or by another fuel delivery device. 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 engine's air system to cause overspeed and severe engine damage. A mishap such as vehicular accident or train wreck may create fugitive fueling situations as well.
Another type of fugitive fueling may occur due to a leak in an engine lubrication system. Such leaks 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 failure in a component such as a turbocharger bearing, or a failure such as the dropping of a cylinder poppet valve. In any case, fugitive fueling may provide hundreds of horsepower worth of fuel to a large engine which is sufficient to cause the engine to overspeed if the engine is unloaded.
Known systems and methods monitor engine speed and attempt to limit overspeeding by controlling fuel delivery. This method of control may not be effective in the case of engines which exhibit overspeeding only after a significant time has passed since the onset of a fugitive fueling event, because the passage of time frequently allows a large quantity of lubricating oil to build up improperly within a location accessible to the engine's air inlet system. Once this occurs, fuel limiting may not be sufficient to prevent a damaging overspeed event.
A need exists for a system and method to detect and respond to fugitive fueling before an engine overspeeds, and indeed, prior to the build-up of lubricating oil which could cause a deleterious overspeed event.
According to an aspect of the present invention, a method for detecting fugitive fueling of an internal combustion engine by monitoring exhaust temperature anomalies includes monitoring at least one exhaust temperature attribute which is a function of the combustion of fugitive fuel within the engine and comparing the value of the at least one temperature attribute with the predetermined threshold value. If the value of the temperature attribute exceeds the threshold value, an engine operator will be notified that fugitive fueling is occurring. Also, remedial action will be taken to prevent engine damage from the fugitive fueling.
According to an aspect of the present invention, an exhaust temperature attribute useful for practicing the invention may be determined as the differences, if any, between the bulk exhaust temperatures of a plurality of separate banks of cylinders of an engine. These differences are preferably measured upstream from a turbocharger connected with, and receiving exhaust from, the separate banks of cylinders. Alternatively, according to an aspect of the present invention, an exhaust temperature attribute useful for practicing the invention may include a bulk exhaust temperature which is compared with a predicted bulk exhaust temperature determined as a function of the contemporaneous power output of the engine. A predicted bulk exhaust temperature may, alternatively, be determined as a function of the quantity of fuel being furnished to the engine's cylinders. As yet another alternative, the bulk exhaust temperature may be compared with the predetermined bulk exhaust temperature drawn from a look up table in the engine's controller. The engine controller preferably comprises at least one microprocessor controller.
According to another aspect of the present invention, a system for detecting fugitive fueling of an internal combustion engine includes a controller for monitoring at least one exhaust temperature attribute which is a function of the combustion of fugitive fuel within the engine. Temperatures may be measured either at individual cylinder banks or as a bulk temperature measured at a flow point in the exhaust system wherein the gasses from all the engine's cylinders have been merged. The system compares either the difference between bulk temperatures of different banks of cylinders or the merged bulk temperature, which is compared with an expected temperature according to the contemporaneous horsepower output of the engine. In the event that either the temperature attribute exceeds the threshold, remedial action will be taken to prevent damage to the engine from fugitive fueling.
It is an advantage of the system according to the present invention that fugitive fueling may be detected rapidly and in sufficient time to take remedial action to avoid damage to an engine.
It is another advantage of a method and system according to the present invention that fugitive fueling may be detected without expensive and complicated sensing and/or analysis of data.
Other advantages, as well as features, of the present invention will become apparent to the reader of this specification.
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Engine 10 also includes a split exhaust system having two exhaust manifolds 18 and 19. Exhaust manifold 18 is connected with exhaust downpipe 20, and exhaust manifold 19 is connected with exhaust downpipe 21. Downpipes 20 and 21 come together at common section 28 before entering turbocharger 22. Exhaust gases entering turbocharger 22 pass through exhaust turbine 26 and then through exhaust pipe 27. Exhaust turbine 26 turns compressor section 30, and air entering turbocharger by means of air inlet 32 is compressed and then enters intercooler 36 before passing into air supply pipe 45 and intake manifold 40. Engine 10 also has a turbo oil supply line, 23, which furnishes lubricating oil to turbocharger 22. Oil leaving the turbocharger passes through return oil line 25.
Air may be prevented from entering intake manifold 40 by means of air shutter 44. Alternatively, engine 10 may be stopped in an emergency by means of inert gas within tank 48 and valve 50, which allows controller 52 (
Engine 10 has a number of exhaust temperature sensors. Sensor 35 measures the exhaust temperature in downpipe 20, whereas sensor 38 measures the temperature in bulk gasses downstream of both sensor 35 and also sensor 34, which measures the exhaust temperature in downpipe 21.
Moving now to
Continuing now with
Remedial action taken in the face of apparent fugitive fueling may include a variety of procedures including: operation of air shutter 44 to starve engine 10 of air; opening of valve 50 to release inert gas into engine 10, again to starve the engine of air; and using self-loading devices, such as resistive elements connected in series with alternator 64 to load engine 10 to an amount exceeding the capability of horsepower generation based on the fugitive fueling. In general, intended fueling will also be ceased immediately upon the suspicion of fugitive fueling.
The remedial action taken in response to apparent fugitive fueling may be rendered more precise by first verifying that fugitive fueling is indeed occurring. This may be accomplished by performing an energy balance on the running engine by comparing the engine's power output with the intentional, or scheduled, fuel flow. In any event, engine 10 will be stopped before damage can occur due to overfueling or fugitive fueling.
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.