Engine variable camshaft timing phaser with planetary gear assembly

An engine variable camshaft timing phaser (10), comprising:

• a sprocket (12) receiving rotational drive input from an engine crankshaft;
• at least two ring gears (26, 28), one of said at least two ring gears (26, 28) receiving rotational drive input from said sprocket (12) and one of said at least two ring gears (26, 28) transmitting rotational drive output to an engine camshaft;
• a plurality of planet gears (24) engaged with said at least two ring gears (26, 28);
• a sun gear (22) engaged with said plurality of planet gears (24);
• a sleeve (78) driven by an electric motor (32);
• a wrap spring (76) located at least partly around said sun gear (22) and at least partly around said sleeve (78);
• wherein, when said sleeve (78) is driven by the electric motor (32), said wrap spring (76) experiences contraction exertion and relative rotation between said sprocket (12) and the engine camshaft is permitted for advancing or retarding engine valve opening and closing, and when the engine camshaft back-drives the engine camshaft timing phaser (10), said wrap spring (76) experiences expansion exertion and relative rotation between said sprocket (12) and the engine camshaft is prevented to preclude advancing or retarding engine valve opening and closing.

An engine variable camshaft timing phaser (10), comprising:

• a sprocket (12) receiving rotational drive input from an engine crankshaft;
• at least two ring gears (26, 28), one of said at least two ring gears (26, 28) receiving rotational drive input from said sprocket (12) and one of said at least two ring gears (26, 28) transmitting rotational drive output to an engine camshaft;
• a plurality of planet gears (24) engaged with said at least two ring gears (26, 28);
• a sun gear (22) engaged with said plurality of planet gears (24), said sun gear (22) having a first wall (48, 50, 52, 54) and a second wall (48, 50, 52, 54);
• a sleeve (78) driven by an electric motor (32), said sleeve (78) having a first wall (98, 100, 102, 104) confronting said first wall (48, 50, 52, 54) of said sun gear (22), said sleeve (78) having a second wall (98, 100, 102, 104) confronting said second wall (48, 50, 52, 54) of said sun gear (22);
• and
• a wrap spring (76) located at least partly around said sun gear (22) and located at least partly around said sleeve (78), said wrap spring (76) having a first end (82) situated between the confrontation of said first walls (48, 50, 52, 54, 98, 100, 102, 104) of said sun gear (22) and sleeve (78), said wrap spring (76) having a second end (84) situated between the confrontation of said second walls (48, 50, 52, 54, 98, 100, 102, 104) of said sun gear (22) and sleeve (78);
• wherein, when said sleeve (78) is driven by the electric motor (32), said first wall (98, 100, 102, 104) of said sleeve (78) or said second wall (98, 100, 102, 104) of said sleeve (78) comes into abutment with said first end (82) of said wrap spring (76) and causes contraction exertion of said wrap spring (76) and permits relative rotation between said sprocket (12) and the engine camshaft for advancing or retarding engine valve opening and closing, and when the engine camshaft timing phaser (10) experiences back-driving, said first wall (48, 50, 52, 54) of said sun gear (22) or said second wall (48, 50, 52, 54) of said sun gear (22) comes into abutment with said second end (84) of said wrap spring (76) and causes expansion exertion of said wrap spring (76) and prevents relative rotation between said sprocket (12) and the engine camshaft to preclude advancing or retarding engine valve opening and closing.