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Diesel engine cylinder deactivation (CDA) can be used to reduce petroleum consumption and greenhouse gas (GHG) emissions of the global freight transportation system. Heavy duty trucks require complex exhaust aftertreatment (A/T) in order to meet stringent emission regulations. Efficient reduction of engine-out emissions require a certain A/T system temperature range, which is achieved by thermal management via control of engine exhaust flow and temperature. Fuel efficient thermal management is a significant challenge, particularly during cold start, extended idle, urban driving, and vehicle operation in cold ambient conditions. CDA results in airflow reductions at low loads. Airflow reductions generally result in higher exhaust gas temperatures and lower exhaust flow rates, which are beneficial for maintaining already elevated component temperatures. Airflow reductions also reduce pumping work, which improves fuel efficiency.

Effective control of exhaust emissions from modern diesel engines requires the use of aftertreatment systems. Elevated aftertreatment component temperatures are required for engine-out emissions reductions to acceptable tailpipe limits. Maintaining elevated aftertreatment components temperatures is particularly problematic during prolonged low speed, low load operation of the engine (i.e. idle, creep, stop and go traffic), on account of low engine-outlet temperatures during these operating conditions. Conventional techniques to achieve elevated aftertreatment component temperatures include delayed fuel injections and over-squeezing the turbocharger, both of which result in a significant fuel consumption penalty. Cylinder deactivation (CDA) has been studied as a candidate strategy to maintain favorable aftertreatment temperatures, in a fuel efficient manner, via reduced airflow through the engine.

A cylinder deactivation system has been developed for use on dual overhead camshaft (DOHC), roller finger follower valvetrain engine applications. Cylinder deactivation is emerging as an effective means to reduce fuel consumption in vehicles, especially those equipped with V6 or V8 engines. This paper addresses a new system that accomplishes this function through the use of a switching roller finger follower (SRFF). This system includes key design features that allow application of the SRFF without affecting overall width, height, or length of DOHC engines. Emphasis was placed on reducing the moment of inertia over the SRFF pivot without compromising rocker arm stiffness. The switching mechanism for transitioning between normal and deactivated operation is hydraulically actuated with engine oil. The switching windows are identified in terms of temperature, pressure, and engine speed. High engine speed test results show stable valvetrain dynamics above 7000 rpm engine speed.