Method of operating an internal combustion engine

Abstract

A method is disclosed for operating an internal combustion engine equipped with an aftertreatment device. The internal combustion engine is equipped with a cylinder having an exhaust gas port intercepted by an exhaust valve, the exhaust valve being actuated by means of a Variable Valve Actuation (VVA) system, An aftertreatment device regeneration is detected, and the exhaust valve closure is anticipated using the Variable Valve Actuation (VVA) system during the aftertreatment device regeneration to provide an exhaust valve actuation profile having an anticipated exhaust valve closure with respect to a baseline exhaust valve actuation profile.

Description

technical field [0001] The invention relates to a method of operating an internal combustion engine. Background technique [0002] Due to continuously stricter emission requirements, internal combustion engines are equipped with aftertreatment exhaust systems such as diesel oxidation catalysts (DOC), diesel particulate filters (DPF), lean NOx adsorption technology (LNT) and / or selective catalytic reduction (SCR) system or SCRF (SCR on filter), etc., the conversion efficiency is strictly related to the exhaust gas temperature. Carbon dioxide levels mandated by future legislation will drive to lower temperatures within the exhaust pipe, creating critical operating conditions that may affect the ability of the aftertreatment system to operate at optimum efficiency. [0003] Several valve control technologies have been developed; one of them is variable valve actuation (VVA), which allows an optimized cam profile for intake and / or exhaust valves in terms of valve timing or lift...

AI Technical Summary

Problems solved by technology

[0008] Another issue is the reduced efficiency of aftertreatment processes such as DPF regeneration or LNT desulfurization due to temperature instability in customer real driving conditions, resulting in high unburned soot residue or low sulfur removal at the end of the regeneration process

This means that increased regeneration duration or frequency is bad for fuel economy due to more regenerations experienced over the life of the component, degraded system performance due to thermal stress or aging due to increased exposure to the high temperatures reached during the regeneration process (oxidizing capacity), potentially detrimental to emissions

Additionally, a high degree of calibration work on the post injection control may be required to allow for a sufficiently stable upstream aftertreatment system temperature in each driving condition

[0009] Finally, the urban cycle is one of the most critical situations for the effectiveness of the regeneration process under the conditions of actual customer driving: frequent operation with acceleration, deceleration and engine idling at lower engine speeds and loads, resulting in Highly variable and unstable temperatures and consequently very complex control of post-injection to ensure desired temperatures are achieved

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