Patent ID: 7559318
Filing Date: 2009-07-14
Classification: F01L,F02B,F02D,F02M,Y02T

Abstract:
1. An apparatus for achieving internal EGR in a four-stroke internal combustion engine, comprising, for each cylinder and piston associated with the cylinder: at least one inlet valve and at least one exhaust valve for controlling connection between a combustion chamber in the cylinder and an inlet system and exhaust system respectively; a rotary camshaft with a cam curve designed to interact with a follower member, the cam curve having a first lobe portion for generating a normal exhaust valve lift of the engine and a second lobe portion having a height measurement over and above a basic curve of the camshaft, the height measurement for the second lobe portion falling short of a height measurement for normal exhaust valve clearance when driving at a first load and heat development in the engine, and which height measurement for the second lobe portion, as a result of thermal expansion in the valve mechanism, exceeds the measurement for normal exhaust valve clearance when driving at a second load and heat development in the engine, the second load and heat development being higher than the first load and heat development, wherein the second lobe portion is situated within a crankshaft angular range of about 360-480 degrees.