Primary and auxiliary rocker arm assembly for engine valve actuation

A system for actuating first and second engine valves comprising:

• a rocker arm shaft;
• a primary rocker arm disposed on the rocker arm shaft, said primary rocker arm having a master piston boss extending laterally from a main body of the primary rocker arm, and having an engine valve actuation end;
• an auxiliary rocker arm disposed adjacent to the main body of the primary rocker arm on a side of the primary rocker arm from which the master piston boss extends;
• a master piston disposed in a master piston bore in the master piston boss;
• a slave piston disposed in a slave piston bore in the main body of the primary rocker arm;
• a valve bridge extending between the first and second engine valves, and having a center surface adapted to contact the primary rocker arm actuation end, said valve bridge further having a side opening extending through a first end of the valve bridge above the first engine valve;
• a sliding pin disposed in the valve bridge side opening and extending between and contacting the first engine valve and the slave piston;
• and
• a hydraulic circuit connecting the master piston bore, the slave piston bore and a hydraulic fluid source.

A method of actuating first and second engine valves for primary and auxiliary valve actuation events using a primary rocker arm, an auxiliary rocker arm mounted adjacent to the primary rocker arm, and a master-slave hydraulic lost motion system incorporated into the primary rocker arm, said method comprising the steps of:

• actuating the first and second engine valves for a primary valve actuation event responsive to motion imparted from a first valve train element to the primary rocker arm during a primary valve actuation mode of engine operation;
• applying hydraulic fluid to the master-slave hydraulic lost motion system to extend master and slave pistons from the primary rocker arm during a time that an auxiliary valve actuation event is to be imparted to only the first of the first and second engine valves;
• and
• actuating only the first of the first and second engine valves for an auxiliary valve actuation event using the master-slave hydraulic lost motion system responsive to motion imparted from a second valve train element to the auxiliary rocker arm during an auxiliary valve actuation mode of engine operation.