Fast warm-up of diesel aftertreatment system during cold start
AssigneeSouthwest Research Institute
InventorYiqun Nuang
Life of this patent
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Abstract
Intake air is severely restricted during cold start of a diesel engine to provide high engine-out exhaust gas temperatures and quickly heat exhaust treatment devices. Cylinder pressures are maintained substantially below the pressure of the ambient atmosphere during a principal portion of the intake stroke of each combustion cycle to promote rapid fuel vaporization and higher combustion temperatures. The engine is operated in a premixed charge compression ignition combustion mode to provide a high engine-out exhaust temperature, stable combustion, and low emissions during the cold start period.
Claims6
A method for the fast warm-up of an exhaust treatment device during cold start of a diesel engine having a plurality of combustion chambers, a means for restricting the flow of an intake air charge into the combustion chambers, a fuel injection system, and a variable geometry turbocharger, said method comprising:
- determining a desired activation temperature for said exhaust treatment device;
- closing said means for restricting the flow of an intake air charge to a position sufficient to provide a combustion chamber pressure of less than 55 kPaabs throughout a principal portion of the intake stoke of each combustion cycle of the engine;
- starting said engine;
- and
- operating said engine at fast idle in a low pressure premixed charge compression ignition combustion mode and increasing the idle speed to a value sufficient to provide an engine-out exhaust gas temperature higher than said determined desired activation temperature of said exhaust treatment device.
Dependencies are inferred from the claim text.