Dual independent phasing system to independently phase the intake and exhaust cam lobes of a concentric camshaft arrangement

A dual independent phasing system (DIPS) phaser assembly for coaxial camshafts comprising:

• first and second phaser subassemblies, each including a rotor with outwardly directed vanes, a stator with inwardly directed projections, each of the vanes extending between a pair of the inwardly directed projections to define pressurized hydraulic fluid chambers for advancing or retarding the rotor relative to the stator, and front and rear covers defining the front and rear walls of the chambers, the rotors being adapted for connection to an inner camshaft and an outer camshaft, respectively;
• a timing gear or pulley connected to the stator of one of the phaser subassemblies, the timing gear or pulley being arranged to transmit radial loads into the outer camshaft;
• the first and second phaser subassemblies are preassembled together as a unit;
• the first and second phaser assemblies are axially arranged adjacent to each other, and the stators of the first and second phaser subassemblies are connected together;
• and
• a helical equalizing spring is located between the first and second phaser assemblies and is connected between the stator and the rotor of the second phaser.