Method and apparatus for gaseous fuel introduction and controlling combustion in an internal combustion engine

A method of introducing fuel into a cylinder of an operating internal combustion engine having a piston disposed within said cylinder, said fuel comprising a main fuel and a pilot fuel that is auto-ignitable to a degree greater than said main fuel, said method comprising introducing fuel into said cylinder in three stages, whereby:

• (a) a first portion of said main fuel is introduced in a first main fuel stage, timed such that said first portion has sufficient time to mix with intake air so that said first portion burns in a pre-mixed combustion mode;
• (b) said pilot fuel is introduced in a pilot stage, such that said pilot fuel auto-ignites when said piston is at or near top dead center;
• and
• (c) a second portion of said main fuel is introduced in a second main fuel stage, such that said second portion burns in a diffusion combustion mode;
• wherein the quantity of said first portion of main fuel is controlled to provide a main fuel to air ratio during a compression stroke that is less than a calibrated knocking limit.

An apparatus for introducing fuel into the cylinder of an operating internal combustion engine having at least one cylinder with a piston disposed therein, said fuel comprising a main fuel and a pilot fuel that is auto-ignitable to a degree greater than said main fuel, said apparatus comprising:

• (a) measuring devices for collecting operational data from said engine, said measuring devices comprising a tachometer for measuring engine speed and a sensor for determining throttle position;
• (b) an electronic control unit that receives said operational data and processes said data to compute a set of load conditions, said electronic control unit comprising memory for storing control sets of load conditions and predetermined operating modes for said control sets of load conditions, said electronic control unit matching said computed set of load conditions with said control sets of load conditions to select one of a plurality of predetermined operating modes;
• (c) a main fuel injection valve controlled by said electronic control unit to introduce said main fuel into said cylinder at times and in quantities determined by said electronic control unit in accordance with said predetermined operating modes and said set of load conditions;
• and
• (d) a pilot fuel injection valve controlled by said electronic control unit to introduce said pilot fuel into said cylinder at times and in quantities determined by said electronic control unit with said predetermined operating modes and said set of load conditions;
• wherein said predetermined operating mode comprises a three stage introduction of fuel into said cylinder, whereby a first portion of said main fuel is introduced in a first stage, said pilot fuel is introduced in a second stage and a second portion of said main fuel is introduced in a third stage.

An apparatus for introducing gaseous fuel into the cylinder of an operating internal combustion engine having at least one cylinder with a piston disposed therein, said apparatus comprising:

• (a) measuring devices for collecting operational data from said engine, said measuring devices comprising a tachometer for measuring engine speed, a sensor for determining throttle position, and a sensor for determining temperature within an air intake manifold;
• (b) an electronic control unit that receives said operational data and processes said data to compute a set of load conditions, said electronic control unit comprising memory for storing control sets of load conditions and predetermined operating modes for said control sets of load conditions, said electronic control unit matching said computed set of load conditions with said control sets of load conditions to select one of a plurality of predetermined operating modes;
• (c) means for controlling temperature within said intake manifold, whereby said means is employed to conform temperature within said intake air manifold with a temperature determined by said electronic control unit with reference to said measured operational data and said computed set of load conditions;
• (d) a gaseous fuel injection valve controlled by said electronic control unit to introduce a portion of said gaseous fuel into said cylinder at times when cylinder intake and exhaust valves are closed, and in quantities determined by said electronic control unit in accordance with said predetermined operating modes;
• and
• (e) an auxiliary gaseous fuel injection valve controlled by said electronic control unit to introduce a portion of said gaseous fuel into an intake air passage to provide a mixture of air and gaseous fuel to said cylinder when said intake valve is open, with said mixture having a fuel to air ratio determined by said electronic control unit based upon said predetermined operating modes;
• wherein for given computed load conditions said predetermined operating mode determines timing and quantity of gaseous fuel introduction into said cylinder, whereby a premixed charge of gaseous fuel and air is introduced through said intake valve to combust within said cylinder in a premixed combustion mode, and gaseous fuel is introduced through said gaseous fuel injection valve to combust within said cylinder substantially in a diffusion combustion mode.