Patent ID: 7281515
Filing Date: 2007-10-16
Classification: F02B,F02D,F02M,Y02T

Abstract:
1. A method of operating an internal combustion engine comprising at least one combustion chamber defined by a cylinder, a piston reciprocable within said cylinder, a cylinder head that covers an end of said cylinder, a piston rod connecting said piston to a crankshaft whereby said crankshaft is rotatable by reciprocal movement of said piston, a fuel injection valve with a nozzle end disposed within said at least one combustion chamber for introducing a gaseous fuel directly into said at least one combustion chamber, and an actuator for said fuel injection valve that is operable to change a commanded amplitude for lifting a valve needle during an injection event, and to change from one combustion cycle to the next combustion cycle the shape of an actuation pulse, which is defined by said commanded amplitude plotted against time, said method comprising: selecting one of at least two predetermined operating modes as a function of engine load and engine speed, wherein a first operating mode is selected when said engine is commanded to operate within a first region corresponding to a low load and low speed range, and a second operating mode is selected when said engine is commanded to operate within a second region distinct from said first region, said second region corresponding to at least one of a greater load range and a greater speed range compared to said first region; and commanding at least one of said actuation pulses to said actuator for each combustion cycle to open said fuel injection valve and introduce said gaseous fuel into said at least one combustion chamber, wherein in said first operating mode, said at least one actuation pulse has a shape that is substantially rectangular, and in said second operating mode, said at least one actuation pulse comprises at least two shape-defining segments with said commanded amplitude for a first segment being less than 90% of said amplitude for a second segment, which occurs after said first segment.