Abstract: An internal combustion engine includes a plurality of cylinders each having intake and exhaust valves and at least one camshaft timed to operate the valves with a high performance fixed overlap. Each camshaft has a cam phaser controlled to equally vary the intake and exhaust valve timing for superior full throttle performance over the engine speed range; Valve deactivation mechanisms operate to deactivate up to half the cylinders during idle and light load operation for increasing fuel efficiency and emission control and maintaining stable operation of the operating cylinders. The engine may also be started with half the cylinders cut out and then run with stable operation in this mode during idle and light load because the increased load on the operating cylinders gives stable operation with an increased valve overlap permitting increased performance and emission control at higher load operation on all the cylinders.

Abstract: A direct acting two-step valve train uses direct acting switching valve lifters combined with high and low lift or no lift cams providing differential valve lifts for dual intake valves of cylinders actuated by the low lift cams. The combination provides various alternative operating modes utilizing the charge enhancing qualities of differential intake valve lifts in low lift operation. These modes include (1) high lift to differential low valve lift and (2) high lift to low lift on one bank and high lift or no lift (deactivated) on the other. A cam phaser may also be included to vary cam phasing on single or dual camshafts.

Abstract: A direct acting two-step valve train uses direct acting switching valve lifters combined with high and low lift or no lift cams providing differential valve lifts for dual intake valves of cylinders actuated by the low lift cams. The combination provides various alternative operating modes utilizing the charge enhancing qualities of differential intake valve lifts in low lift operation. These modes include (1) high lift to differential low valve lift and (2) high lift to low lift on one bank and high lift or no lift (deactivated) on the other. A cam phaser may also be included to vary cam phasing on single or dual camshafts.

Abstract: A rocker arm assembly includes an inner rocker arm and an outer rocker arm. The outer rocker arm includes two rail portions spaced a distance apart and forming an open space therebetween. The inner rocker arm is pivotably connected to the outer rocker arm such that it is at least partially within the open space. The inner rocker arm includes a locking pin housing containing two locking pins selectively engageable with holes in each of the rail portions to selectively prevent relative movement between the inner rocker arm and the outer rocker arm. The rocker arm assembly enables two-step valve operation and has a design characterized by compact size and improved manufacturability.

Abstract: A lubrication system for an internal combustion engine includes a variable displacement oil pump supported on the engine block and connected to draw oil from the oil pan and to supply pressurized oil to various engine components. The pump defines variable displacement pumping chambers for carrying oil from an inlet to a pressurized outlet. An exemplary embodiment includes a vane pump with a feedback displacement control using pressure from the lubrication system to actuate a slide ring in the pump to control the pump output. Numerous features of the pump are disclosed.

Abstract: A lubrication system for an internal combustion engine includes a variable displacement oil pump supported on the engine block and connected to draw oil from the oil pan and to supply pressurized oil to various engine components. The pump defines variable displacement pumping chambers for carrying oil from an inlet to a pressurized outlet. An exemplary embodiment includes a vane pump with a feedback displacement control using pressure from the lubrication system to actuate a slide ring in the pump to control the pump output. Numerous features of the pump are disclosed.

Abstract: A method is provided for forming enlarged cylinder bores in an engine based on a family of internal combustion engines having an original cylinder bore axis for each bore, wherein each cylinder bore is constrained against enlargement toward one side. The method includes providing an offset axis parallel to the original cylinder bore axis and spaced toward an opposite side of the cylinder bore by a dimension equal to one half of a predetermined bore diameter enlargement, and centering the enlarged cylinder bore on the offset axis. The method preserves a minimum wall thickness from the cylinders to camshaft bores between the cylinder banks while the outward enlargement dimension is preferably limited to a value which does not require changing the cylinder head bolt pattern or reduce the wall thickness below minimum values in other portions of the cylinders.

Abstract: A method is provided for forming enlarged cylinder bores in an engine based on a family of internal combustion engines having an original cylinder bore axis for each bore, wherein each cylinder bore is constrained against enlargement toward one side. The method includes providing an offset axis parallel to the original cylinder bore axis and spaced toward an opposite side of the cylinder bore by a dimension equal to one half of a predetermined bore diameter enlargement, and centering the enlarged cylinder bore on the offset axis. The method preserves a minimum wall thickness from the cylinders to camshaft bores between the cylinder banks while the outward enlargement dimension is preferably limited to a value which does not require changing the cylinder head bolt pattern or reduce the wall thickness below minimum values in other portions of the cylinders.

Abstract: A rocker arm assembly includes an inner rocker arm and an outer rocker arm. The outer rocker arm includes two rail portions spaced a distance apart and forming an open space therebetween. The inner rocker arm is pivotably connected to the outer rocker arm such that it is at least partially within the open space. The inner rocker arm includes a locking pin housing containing two locking pins selectively engageable with holes in each of the rail portions to selectively prevent relative movement between the inner rocker arm and the outer rocker arm. The rocker arm assembly enables two-step valve operation and has a design characterized by compact size and improved manufacturability.

Abstract: An internal combustion engine has a crankcase, a cylinder bank extending from the crankcase and a crankshaft disposed in the crankcase. A cylinder in the cylinder bank is closed by a cylinder head which carries intake and exhaust valves for regulating the flow of gasses through the cylinder. An intake and an exhaust camshaft are rotationally disposed within the crankcase and are driven by the crankshaft. The intake camshaft has a cam lobe which operates the intake valve through a pushrod extending between the cam lobe and the valve and the exhaust camshaft has a cam lobe which operates the exhaust valve through a pushrod extending between the cam lobe and the valve. The use of separate intake and exhaust camshafts separates the intake valve actuation event from that of the exhaust valve and allows the application of camshaft phasing to vary the opening relationship, or timing of the intake and the exhaust valves. In addition, the use of two camshafts facilitates the use of multi-step cam lobe.