Multi-fuel compression ignition engine

A method comprising:

• supplying a relatively large volume of a liquid primary fuel to a combustion chamber of a compression ignition engine so as to form a homogeneous mixture of said primary fuel and air in said combustion chamber;
• injecting a relatively small volume of a pilot fuel into said combustion chamber, said pilot fuel having a lower autoignition temperature than said primary fuel and having a relatively narrow boiling point temperature range;
• and
• autoigniting said pilot fuel by compression ignition and igniting said primary fuel through combustion of said pilot fuel, thereby obtaining pilot assisted HCCI combustion of said primary fuel.

A method comprising:

• A) injecting a liquid fuel into an air stream so as to form a homogeneous mixture of air and atomized droplets of fuel having a mean diameter of less than about 50 microns;
• B) admitting said mixture into a combustion chamber of an internal combustion engine;
• and
• C) igniting the liquid fuel in said mixture by compression ignition so as to achieve homogeneous charge compression ignition (HCCI) of said liquid fuel, wherein, after the injecting step, said liquid fuel evaporates and cools the air in said mixture.

A method comprising:

• A) injecting a liquid fuel into an air stream so as to form a homogeneous mixture of air and atomized droplets of fuel having a mean diameter of less than about 50 microns;
• B) admitting said mixture into a combustion chamber of an internal combustion engine;
• and
• C) igniting the liquid fuel in said mixture by compression ignition so as to achieve homogeneous charge compression ignition (HCCI) of said liquid fuel, wherein said liquid fuel is injected via a plurality of fogging nozzles, and further comprising adjusting a fuel supply quantity by at least one of
• A) adjusting fuel supply pressure;
• B) pulse-width-modulating flow through at least one of said nozzles;
• C) varying an orifice diameter of at least one of said nozzles;
• and
• D) disabling at least one of said nozzles.

A method comprising:

• A) injecting a liquid fuel into an air stream so as to form a homogeneous mixture of air and atomized droplets of fuel having a mean diameter of less than about 50 microns;
• B) admitting said mixture into a combustion chamber of an internal combustion engine;
• and
• C) igniting the liquid fuel in said mixture by compression ignition so as to achieve homogeneous charge compression ignition (HCCI) of said liquid fuel , wherein
• said liquid fuel is a primary fuel, and further comprising injecting a relatively small volume of a pilot fuel into said combustion chamber, said pilot fuel having a lower autoignition temperature than said primary fuel and having a relatively narrow boiling point temperature range;
• and wherein
• the compression ignition step comprises autoigniting said pilot fuel by compression ignition and igniting said primary fuel through combustion of said pilot fuel, thereby obtaining pilot assisted HCCI of said primary fuel.

A method comprising:

• A) injecting a liquid fuel into an air stream so as to form a homogeneous mixture of air and atomized droplets of fuel having a mean diameter of less than about 50 microns;
• B) admitting said mixture into a combustion chamber of an internal combustion engine;
• and
• C) igniting the liquid fuel in said mixture by compression ignition so as to achieve homogeneous charge compression ignition (HCCI) of said liquid fuel,
• wherein a turbocharger and a cooler are located in series in an air intake passage through which said air stream passes, and wherein the injecting step comprises injecting the liquid fuel into the air intake passage upstream of the turbocharger.

A method of operating an engine having a cylinder which includes an engine head and a piston which is reciprocateably translatable in the cylinder to define a variable-volume combustion chamber between the engine head and the piston, the method comprising the steps of:

• (A) performing an intake stroke of the piston;
• (B) performing a compression stroke of the piston after the intake stroke;
• (C) admitting a homogeneous charge of a liquid fuel and air into the combustion chamber during one of the intake stroke and the compression stroke, said homogeneous charge being formed by injecting said liquid fuel into the intake air stream in the form of atomized droplets having a mean diameter of less than about 30 microns;
• (D) injecting a pilot fuel charge into the combustion chamber during the compression stroke, said pilot fuel having a lower autoignition temperature than said primary fuel and having a relatively narrow boiling point temperature range;
• (E) combusting said pilot fuel charge to ignite said primary fuel by HCCI, wherein the steps of injecting the pilot fuel charge and igniting the pilot fuel charge comprise, on a cycle-by-cycle, full load and speed range basis
• (1) initiating pilot fuel injection at a time, Tp,
• (2) continuing pilot fuel injection for a duration, Dp, and
• (3) igniting the pilot fuel charge by compression-ignition at an autoignition point, Ti, occurring an ignition delay interval Di after Tp;
• and
• (4) controlling at least one of Tp, Dp, and Di to maintain Dp/Di<1.