Development of a Switching Roller Finger Follower for Cylinder Deactivation in Gasoline Engine Applications

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. Testing results show that this technology is robust and meets the required dynamic performance that make this technology a viable option for capturing fuel economy improvements on passenger car engines.