Method for variable valve timing for an internal combustion engine

Abstract

Abstract The apparatus for cyclically actuating an actuation member has a hollow shaft (12) rotatable about an axis (14) of rotation and having a cam opening (34) therethrough, an inner shaft (16) rotatably carried within the hollow shaft, camlobe members (36 and 28), respectively fixed to the hollow shaft (12) adjacent the cam opening (34) and to the inner shaft and projecting through the cam opening (34). A variable transmission (38) has a reference element (40, 42) connected to one of the shafts (12), an output element (52, 54) connected to the other of the shafts (16), and an input element (58); a pulley wheel (50) is connected to the shafts for rotating same about the axis (14), and an electric motor (72) is drivingly connected to the input element (58), and is controlled by an electronic control unit (84) which can include one or more microprocessor units. The apparatus can be utilized to actuate and deactuate one or both of the intake valve and exhaust valve of an internal combustion engine. A method of attaining a desired engine performance comprises the steps of changing the angular position of a variable camlobe (or cam) member (28) relative to a fixed camlobe (or cam) member (36) from a first angular position to a second angular position, by a movement of the former in a predetermined direction relative to the direction of rotation of a camshaft. The predetermined direction and the magnitude of the angular movement of the variable camlobe (or cam) member (28) is dependent at least in part upon at least one desired operating condition of the engine. Both camlobe (or cam) members (28, 36) may be moved relative to a reference point of a drive pulley. A method is provided for reducing pumping losses in an internal combustion engine, comprising the steps of inducting a charge of fluid into the engine's combustion chamber, holding the intake valve of the combustion chamber open during a portion of the compression stroke of the piston in the combustion chamber, expelling a portion of the inducted charge from the combustion chamber by movement of the piston in its compression stroke while the intake valve is held open, preventing the expelled portion of the inducted charge from communicating with the atmosphere by a check valve between the induction manifold and the atmosphere, and closing the intake valve during the remainder of the compression stroke and after the portion of the induction charge is expelled.

Inventors

• 👤 Alvon C. Elrod
• 👤 Michael T. Nelson

Bibliographic Details