Torque control strategy for a diesel engine during lean-rich modulation using independent fuel injection maps
View Patent ↗A compression ignition engine ( 10 ) for a motor vehicle has a control system ( 20 ) for processing data, one or more combustion chambers ( 12 ), and fuel injectors ( 18 ) for injecting fuel into the chambers. The control system controls lean-rich modulation of fueling using independent maps. One set of maps is a set of lean fueling maps, and another set is a set of rich fueling maps. The strategy is represented by a flow diagram ( 30 ) and is useful in regenerating a NO x adsorber catalyst ( 16 ) in the engine exhaust system ( 14 ) in a manner that controls torque so that the regeneration process is transparent to the operator of the vehicle.
1. A method of operating a compression ignition engine to accomplish lean-rich modulation of fueling, the method comprising:
processing certain data to modulate fueling between lean modulation and rich modulation;
during lean modulation, processing data representing a particular set of operating conditions to select a particular lean fueling map that comprises fueling data appropriate to the particular set of operating conditions for causing the engine to be fueled in a manner that causes the engine to run lean and develop a corresponding torque; and
during rich modulation, processing data representing substantially the same particular set of operating conditions to select a particular rich fueling map that comprises fueling data appropriate to that substantially same particular set of operating conditions for causing the engine to be fueled in a manner that causes the engine to run rich and develop substantially the same corresponding torque as during lean modulation.
2. A method as set forth in claim 1 wherein during lean modulation, the particular lean fueling map selected causes the engine to be fueled by a main fuel injection without post-injection.
3. A method as set forth in claim 1 wherein during lean modulation, the particular lean fueling map selected causes the engine to be fueled by a one or more pilot injections followed by a main fuel injection without post-injection.
4. A method as set forth in claim 1 wherein during rich modulation, the particular rich fueling map selected causes the engine to be fueled by a main fuel injection with post-injection.
5. A method as set forth in claim 1 wherein during rich modulation, the particular rich fueling map selected causes the engine to be fueled by a one or more pilot injections followed by a main fuel injection with post-injection.
6. A compression ignition engine comprising:
a control system for processing data including a set of lean fueling maps and a set of rich fueling maps;
one or more combustion chambers; and
a fueling system for injecting fuel into the one or more combustion chambers;
wherein the control system at times modulates fueling between lean modulation and rich modulation, and
for lean modulation, processes data representing a particular set of operating conditions to select a particular lean fueling map that comprises fueling data appropriate to the particular set of operating conditions for causing the engine to be fueled in a manner that causes the engine to run lean and develop a corresponding torque; and
for rich modulation, processes data representing substantially the same particular set of operating conditions to select a particular rich fueling map that comprises fueling data appropriate to that substantially same particular set of operating conditions for causing the engine to be fueled in a manner that causes the engine to run rich and develop substantially the same corresponding torque as during lean modulation.
7. An engine as set forth in claim 6 wherein for lean modulation, the control system selects a particular lean fueling map that causes the engine to be fueled by a main fuel injection without post-injection.
8. An engine as set forth in claim 6 wherein for lean modulation, the control system selects a particular lean fueling map that causes the engine to be fueled by one or more pilot injections followed by a main fuel injection without post-injection.
9. An engine as set forth in claim 6 wherein for rich modulation, the control system selects a particular rich fueling map that causes the engine to be fueled by a main fuel injection with post-injection.
10. An engine as set forth in claim 6 wherein for rich modulation, the control system selects a particular rich fueling map that causes the engine to be fueled by one or more pilot injections followed by a main fuel injection with post-injection.
11. A method of operating a compression ignition engine to accomplish lean-rich modulation of fueling for regeneration of a NO x adsorber catalyst in an exhaust system of the engine, the method comprising:
processing certain data to modulate fueling between lean modulation and rich modulation;
during lean modulation, processing data representing a particular set of operating conditions to select a particular lean fueling map that comprises fueling data appropriate to the particular set of operating conditions for causing the engine to be fueled in a manner that causes the engine to run lean and develop a corresponding torque; and
during rich modulation, processing data representing substantially the same particular set of operating conditions to select a particular rich fueling map that comprises fueling data appropriate to that substantially same particular set of operating conditions for causing the engine to be fueled in a manner that causes the engine to run sufficiently rich to create sufficient carbon monoxide for regenerating the NO x adsorber catalyst while developing substantially the same corresponding torque as during lean modulation.
12. A method as set forth in claim 11 wherein during lean modulation, the particular lean fueling map selected causes the engine to be fueled by a main fuel injection without post-injection.
13. A method as set forth in claim 11 wherein during lean modulation, the particular lean fueling map selected causes the engine to be fueled by a one or more pilot injections followed by a main fuel injection without post-injection.
14. A method as set forth in claim 11 wherein during rich modulation, the particular rich fueling map selected causes the engine to be fueled by a main fuel injection with post-injection.
15. A method as set forth in claim 11 wherein during rich modulation, the particular rich fueling map selected causes the engine to be fueled by a one or more pilot injections followed by a main fuel injection with post-injection.
16. A compression ignition engine comprising:
a control system for processing data including a set of lean fueling maps and a set of rich fueling maps;
one or more combustion chambers;
a fueling system for injecting fuel into the one or more combustion chambers; and
an exhaust system having a NO x adsorber catalyst through which exhaust from the combustion chambers is constrained to pass;
wherein the control system at times modulates fueling between lean modulation and rich modulation for regenerating the NO x adsorber catalyst, and
for lean modulation, processes data representing a particular set of operating conditions to select a particular lean fueling map that comprises fueling data appropriate to the particular set of operating conditions for causing the engine to be fueled in a manner that causes the engine to run lean and develop a corresponding torque; and
for rich modulation, processes data representing substantially the same particular set of operating conditions to select a particular rich fueling map that comprises fueling data appropriate to that substantially same particular set of operating conditions for causing the engine to be fueled in a manner that causes the engine to run sufficiently rich to create sufficient carbon monoxide for regenerating the NO x adsorber catalyst while developing substantially the same corresponding torque as during lean modulation.
17. An engine as set forth in claim 16 wherein for lean modulation, the control system selects a particular lean fueling map that causes the engine to be fueled by a main fuel injection without post-injection.
18. An engine as set forth in claim 16 wherein for lean modulation, the control system selects a particular lean fueling map that causes the engine to be fueled by one or more pilot injections followed by a main fuel injection without post-injection.
19. An engine as set forth in claim 16 wherein for rich modulation, the control system selects a particular rich fueling map that causes the engine to be fueled by a main fuel injection with post-injection.
20. An engine as set forth in claim 16 wherein for rich modulation, the control system selects a particular rich fueling map that causes the engine to be fueled by one or more pilot injections followed by a main fuel injection with post-injection.