Patent Application
20080078236
The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.
The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. As used herein, the term module refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable components that provide the described functionality.
Referring now to
A turbocharged diesel engine system 10 includes an engine 12 that combusts an air and fuel mixture to produce drive torque. Air enters the system by passing through an air filter 14. Air passes through the air filter 14 and is drawn into a turbocharger 18. The turbocharger 18 compresses the fresh air entering the system 10. The greater the compression of the air generally, the greater the output of the engine 12. Compressed air then passes through an air cooler 20 before entering into an intake manifold 22.
Air within the intake manifold 22 is distributed into cylinders 26. Although four cylinders 26 are illustrated, it is appreciated that the systems and methods of the present invention can be implemented in engines having a plurality of cylinders including, but not limited to, 2, 3, 4, 5, 6, 8, 10 and 12 cylinders. It is also appreciated that the systems and methods of the present invention can be implemented in a v-type cylinder configuration. Fuel is injected into the cylinders 26 by fuel injectors 28. Heat from the compressed air ignites the air/fuel mixture. Combustion of the air/fuel mixture creates exhaust. Exhaust exits the cylinders 26 into the exhaust system.
The exhaust system includes an exhaust manifold 30, a diesel oxidation catalyst (DOC) 32, and a particulate filter (PF) 34. Optionally, an EGR valve (not shown) re-circulates a portion of the exhaust back into the intake manifold 22. The remainder of the exhaust is directed into the turbocharger 18 to drive a turbine. The turbine facilitates the compression of the fresh air received from the air filter 14. Exhaust flows from the turbocharger 18 through the DOC 32 and the PF 34. The DOC 32 oxidizes the exhaust based on the post combustion air/fuel ratio. The amount of oxidation increases the temperature of the exhaust. The PF 34 receives exhaust from the DOC 32 and filters any soot particulates present in the exhaust.
A control module 44 controls the engine and PF regeneration based on various sensed information. A first pressure sensor senses a differential in pressure of exhaust gases flowing through the PF and generates a first pressure sensor signal accordingly. As can be appreciated, other sensors and methods may be employed to sense or determine a pressure differential in the PF 34. The control module 44 receives the pressure sensor signal and determines a PF pressure drop based on drop measurement methods and systems as will be discussed further below. The control module 44 thereafter estimates loading of the PF 34 based on the pressure drop. When the estimated loading achieves a threshold level (e.g., 5 grams/liter of particulate matter) and the exhaust flow rate is within a desired range, the regeneration process is initiated. The duration of the regeneration process varies based upon the amount of particulate matter determined to be within the PF 34.
With particular reference to
With reference to
The clean filter estimating module 70 monitors regeneration event conditions to determine when the PF 34 is clean and sets an enable status flag 76 accordingly. In various embodiments, the clean filter estimating module 70 monitors a regeneration time 80, a regeneration temperature 82, and a regeneration complete status indicator 78 to ensure that regeneration has completed and that the PF 34 is clean. For example, if the regeneration status indicator 78 indicates that regeneration is complete, the regeneration time 80 indicates that regeneration occurred for a predetermined time, and the regeneration temperature 82 indicates that the PF temperature was equal to or above a predetermined temperature threshold during regeneration, the PF 34 is deemed clean and the enable status flag 76 is set to TRUE. Otherwise, the enable status flag 76 remains set to FALSE.
As can be appreciated, the clean filter estimating module 70 may also monitor engine system enable conditions to determine an appropriate time to perform an adaptive learn once the PF 34 is clean. Such engine system enable conditions can include, but are not limited to, speed 84 and load 86. For example, if the speed 84 and load 86 conditions are within predetermined ranges respectively, the enable status flag 76 is set to TRUE. Otherwise, the enable status flag 76 remains set to FALSE.
The adaptive learn module 72, once enabled via the enable status flag 76, adaptively learns pressure drop values 88 and stores the values in memory 90 for later use. In various embodiments, a pressure drop value 91 for a given flow rate 92 and PF temperature 94 is measured once the PF 34 is clean. The measured pressure drop 91 is then stored as clean filter pressure drop 85 in a two-dimensional clean pressure drop table accessed by PF temperature 94 and volume flow rate 92. The soot prediction module 74 estimates a level of soot 96 in the PF 34 based on a total measured pressure of the PF 98, values 88 from the clean filter pressure table, a PF temperature 94, and a volume flow rate 92. More particularly, the soot prediction module 74 measures at total pressure drop 98 across the PF 34; and retrieves a clean pressure drop 88 from the clean filter table based on PF temperature 94 and volume flow rate 92. Based on the total pressure drop (TP) 98, the clean pressure drop (CP) 88, and the flow rate 92, the soot prediction module 74 computes a resistance flow rate (RF) as shown by the following equation:
RF=(TP−CP)/FR (1)
The soot prediction module 74 then uses the computed resistance flow to determine a soot accumulation level 96. In various embodiments, a soot accumulation level 96 is estimated based on a two-dimensional lookup table defined by the volume flow rate 92 and the resistance flow.
With reference to
Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present disclosure can be implemented in a variety of forms. Therefore, while this disclosure has been described in connection with particular examples thereof, the true scope of the disclosure should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification, and the following claims.
