24 th American Control Conference June 8-10, 2005 Diesel Engines Offer superior fuel economy, albeit at higher cost and complexity of the aftertreatment system Achieved remarkable passenger car market penetration in Europe and growing presence in North America Thanks to advances in technology and controls, diesel engines are no longer sluggish nor spewing clouds of black smoke Used also in commercial heavy vehicles, off-road, construction, marine and power generation applications Constitute more than 90 percent of “prime movers”
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24th American Control Conference
June 8-10, 2005
Diesel Engines
� Offer superior fuel economy, albeit at higher cost and complexity of the aftertreatment system
� Achieved remarkable passenger car market penetration in Europe and growing presence in North America� Thanks to advances in technology and controls, diesel engines
are no longer sluggish nor spewing clouds of black smoke
� Used also in commercial heavy vehicles, off-road, construction, marine and power generation applications� Constitute more than 90 percent of “prime movers”
�
24th American Control Conference
June 8-10, 2005
Modern Diesel Engines
� Compression Ignition DI
� Variable Geometry Turbocharged (VGT)
� Operate lean and require lean aftertreatment system
� Use high EGR rates
� Fueling rate is a primary actuator for torque management
� Fuel rate shaping and multiple injections for torque, noise and emission control
� Higher order than for gasoline engines� Contains significant nonlinearities� Contains delays � Using physics-based characterizations is advantageous� Sub-models becomes parts of the control strategy� Analysis goals may necessitate additional modeling
� Crank angle resolved cylinder-by-cylinder behavior� Uncertainties due to part-to-part variability, aging, operating
conditions� Aftertreatment system
24th American Control Conference
June 8-10, 2005
Static Subsystem Interactions
MAP – Manifold Air Pressure
MAF – Compressor Mass Air Flow
“b” – nominal operating point:
(Maximizes burnt gas fraction subject to constraint on AFR)
iP=
cW=
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24th American Control Conference
June 8-10, 2005
Static Subsystem Interactions (cont’d)
Coordinated EGR/VGT ControlInstability Caused by Gain Reversal and Incorrect Set-
Points
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24th American Control Conference
June 8-10, 2005
Dynamic Interactions
� Engine dynamics become slower with EGR valve opening
� Non-minimum phase behavior for a usual selection of outputs