Cam torque actuated phaser with mid position lock

A variable cam timing phaser for an internal combustion engine is having at least one camshaft (68) comprising:

• a housing (10) connected coaxially with respect to a camshaft (68) and defining at least one cavity (10a);
• a rotor (20) rotatable coaxially with respect to the housing (10) and having a vane (22) located within each cavity (10a) of the housing (10) and dividing each cavity (10a) into a first chamber (16) and a second chamber (18);
• an endplate (64) enclosing the rotor (20) with respect to the housing (10), one of the rotor (20) and the endplate (64) having a fixed angular position with respect to a sprocket (70);
• a detent passage (56, 58) extending through the rotor (20) and through the endplate (64) to be in fluid communication with each of the first and second chambers (16, 18), where fluid flow with respect to the fust and second chambers (16, 18) is controlled in response to a relative angular position of the rotor (20) and the endplate (64) with respect to one another;
• a lock pin (60) moveable between a locked position and a released position;
• and
• a detent valve (50) located in the detent passage (56, 58) and moveable between an open position corresponding to the lock pin (60) being in the locked position, and a closed position corresponding to the lock pin (60) being in the released position, when in the open position a pressurized actuating fluid supply source (46) is in fluid communication with the detent passage (56, 58) extending through the rotor (20) and endplate (64) and is controlled in response to a relative angular position of the rotor (20) with respect to the endplate (64).

A cam torque actuated variable cam timing phaser for an internal combustion engine having at least one camshaft (68) comprising:

• a housing (10) connected coaxially with respect to the camshaft (68) and defining at least one cavity (10a);
• a rotor (20) rotatable coaxially with respect to the housing (10) and having a vane (22) rotatably located within each cavity (10a) of the housing (10) and dividing each cavity (10a) into a first chamber (16) and a second chamber (18);
• an endplate (64) enclosing the rotor (22) with respect to the housing (10), one of the rotor (20) and the endplate (64) having a fixed angular position with respect to a sprocket (70);
• a detent passage (56, 58) extending through the rotor (20) and through the endplate (64) to be in fluid communication with each of the first and second chambers (16, 18), where fluid flow with respect to the first and second chambers (16, 18) is controlled in response to a relative angular position of the rotor (20) and the endplate (64) with respect to one another;
• a spring biased lock pin (60) moveable between a locked position providing base timing and a released position;
• a spring biased detent valve (50) in an open position when the lock pin (60) is in the locked position and in a closed position when the lock pin (60) is in the released position;
• a control valve (24) having a spring biased spool (36) with a spring biased first check valve (40) and a spring biased second check valve (42) disposed within the spool (36), the spool (36) operably connecting an actuating fluid supply source (46) selectively between the first chamber (16) and the second chamber (18) through the rotor (20), and operably connecting the lock pin (60) and detent valve (50) between an exhaust vent (48) and the actuating fluid supply source (46) through the detent passage (56, 58) extending through the rotor (20) and endplate (64);
• and
• a variable force solenoid (32) operating the spool (36) of the control valve (24) in response to input from an engine control unit (34), the variable force solenoid (32) selectively moving the spool (36) of the control valve (24) between a first position corresponding to a base timing position, where the lock pin (60) is in the locked position and the detent valve (50) is in the open position allowing fluid communication between a pressurized actuating fluid supply (46) and the detent passage (56, 58) to be controlled in response to a relative angular position of the rotor (20) with respect to the endplate (64), a second position corresponding to an advance timing position, where cam torque actuation forces drive actuating fluid from the second chamber (18) through the spool (36) of the control valve (24) to the first chamber (16), the lock pin (60) is in the released position and the detent valve (50) is in the closed position, a third position corresponding to a retard timing position, where cam torque actuation forces drive actuating fluid from the first chamber (16) through the spool (36) of the control valve (24) to the second chamber (18), the lock pin (60) is in the released position and the detent valve (50) is closed, and a fourth position corresponding to a phaser holding position, where the first and second chambers (16, 18) are isolated from one another by the position of the spool (36) of the control valve (24) and closure of the first and second check valves (40, 42), the lock pin (60) is in the released position and the detent valve (50) is in the closed position.