Cylinder pressure based optimization control for compression ignition engines

A compression ignition internal combustion engine comprising:

• (A) a plurality of cylinders each having an intake port and exhaust port;
• (B) a fuel supply system which selectively supplies a fuel to said cylinders, wherein said fuel is one which ignites by compression;
• (C) an air supply system which supplies air to said intake ports of said cylinders during engine operation, wherein said air supply system comprises
• (1) a turbocharger having an air outlet in fluid communication with the intake ports of the cylinders and having an air inlet, and
• (2) a supercharger having an air outlet in fluid communication with said air inlet of said turbocharger and having an air inlet, and
• (3) a control device which is coupled to said electronic control means and which selectively controls operation of said supercharger;
• (D) a sensor which directly senses pressure within one of said cylinders;
• and
• (E) electronic control means for controlling operation of at least one of said air supply system and said fuel supply system to:
• (1) determine, based upon signals received from said sensor, an actual cylinder pressure-dependent parameter of said engine prevailing at the time of said measurement,
• (2) determine an optimum value of said parameter for optimizing a selected engine performance characteristic at a prevailing engine operating condition, and
• (3) automatically adjust at least one engine operating characteristic so as to cause said actual value of said parameter to approach said optimum value of said parameter.

A compression ignition internal combustion engine comprising:

• (A) a plurality of cylinders each having an intake port and exhaust port;
• (B) a fuel supply system which selectively supplies a fuel to said cylinders, wherein said fuel is one which ignites by compression;
• (C) an air supply system which supplies air to said intake ports of said cylinders during engine operation;
• (D) a sensor which directly senses pressure within one of said cylinders;
• and
• (E) electronic control means for controlling operation of at least one of said air supply system and said fuel supply system, in order to
• (1) determine, based upon signals received from said sensor, an actual cylinder pressure-dependent parameter of said engine prevailing at the time of said measurement,
• (2) determine an optimum value of said parameter for optimizing a selected engine performance characteristic at a prevailing engine operating condition, and
• (3) automatically adjust at least one engine operating characteristic so as to cause said actual value of said parameter to approach said optimum value of said parameter wherein said parameter is a cylinder pressure ratio, CPR, wherein said electronic control means is operable to determine CPR by, during each thermodynamic cycle in which pressure is sensed, 1) obtaining signals from said sensor inductive of first and second cylinder pressures, Pa and Po, prevailing at two different times during each thermodynamic cycle and 2) dividing Pa by Po to obtain CPR.

A method of optimizing operation of a compression ignition engine, comprising:

• (A) directly sensing pressure within a cylinder of said compression ignition engine during engine operation;
• (B) determining, from said measurement, an actual cylinder pressure-dependent parameter of said engine prevailing at the time of said measurement, wherein said parameter is a cylinder pressure ratio, CPR, and wherein CPR is determined by, during each thermodynamic cycle in which pressure is sensed, 1) sensing first and second cylinder pressures, Pa and Po, at two different times during each thermodynamic cycle and 2) dividing Pa by Po to obtain CPR;
• (C) determining an optimum value of said parameter for optimizing a selected engine performance characteristic at a prevailing engine operating condition;
• (D) automatically adjusting at least one engine operating characteristics so as to cause said actual value of said parameter to approach said optimum value of said parameter.

A method of optimizing operation of a compression ignition engine, comprising:

• (A) directly sensing pressure within a cylinder of said compression ignition engine during engine operation;
• (B) determining, from said measurement, an actual cylinder pressure-dependent parameter of said engine prevailing at the time of said measurement;
• (C) determining an optimum value of said parameter for optimizing a selected engine performance characteristic at a prevailing engine operating condition, wherein the engine operation characteristic is lambda;
• (D) automatically adjusting said operating characteristic so as to cause said actual value of said parameter to approach said optimum value of said parameter, wherein the adjusting step comprises adjusting inlet air pressure for said compression ignition engine.

A method of optimizing operation of a compression ignition engine, comprising:

• (A) directly sensing pressure within a cylinder of said compression ignition engine during engine operation;
• (B) determining, from said measurement, an actual cylinder pressure-dependent parameter of said engine prevailing at the time of said measurement;
• (C) determining an optimum value of said parameter for optimizing a selected engine performance characteristic at a prevailing engine operating condition;
• (D) automatically adjusting at least one engine operating characteristics so as to cause said actual value of said parameter to approach said optimum value of said parameter;
• and
• (E) during at least selected thermodynamic cycles, determining the location and value of a maximum cylinder pressure, MCP.

A method of optimizing operation of a compression ignition engine, comprising:

• (A) directly sensing pressure within a cylinder of said compression ignition engine during engine operation;
• (B) determining, from said measurement, an actual cylinder pressure-dependent parameter of said engine prevailing at the time of said measurement;
• (C) determining an optimum value of said parameter for optimizing a selected engine performance characteristic at a prevailing engine operating condition, wherein the engine operation characteristic is lambda;
• (D) automatically adjusting at least one engine operating characteristics so as to cause said actual value of said parameter to approach said optimum value of said parameter, wherein the adjusting step comprises adjusting the operation of a supercharger which is located in series with a turbocharger thereby to adjust inlet air pressure for said turbocharger.

A method of optimizing operation of a compression ignition engine, comprising:

• (A) directly sensing pressure within a cylinder of said compression ignition engine during engine operation;
• (B) determining, from said measurement, an actual cylinder pressure-dependent parameter of said engine prevailing at the time of said measurement;
• (C) determining an optimum value of said parameter for optimizing a selected engine performance characteristic at a prevailing engine operating condition;
• (D) automatically adjusting at least one engine operating characteristics so as to cause said actual value of said parameter to approach said optimum value of said parameter;
• (E) determining a difference in crank angle between a first pressure value obtained during a compression stroke of a thermodynamic cycle and a second pressure value obtained during an expansion stroke of said thermodynamic cycle;
• and
• (F) determining, using the determined crank angle difference, at least one of lambda and a cylinder pressure ratio (CPR).

A method of optimizing operation of a compression ignition engine, comprising:

• (A) directly sensing pressure within a cylinder of said compression ignition engine during engine operation;
• (B) determining, from said measurement, an actual cylinder pressure-dependent parameter of said engine prevailing at the time of said measurement;
• (C) determining an optimum value of said parameter for optimizing a selected engine performance characteristic at a prevailing engine operating condition;
• (D) automatically adjusting at least one engine operating characteristics so as to cause said actual value of said parameter to approach said optimum value of said parameter, wherein said compression ignition engine is a liquid-fueled engine.

A method of optimizing operation of a compression ignition engine, comprising, for each cylinder of said compression ignition engine and during each thermodynamic cycle of said compression ignition engine:

• (A) directly sensing first and second values, Po and Pa, of absolute pressure within the cylinder, wherein Po is sensed during a compression stroke of the thermodynamic cycle and Pa is sensed after the end of combustion, and wherein Po and Pa are sensed using an in-cylinder optic fiber optic sensor;
• (B) dividing Pa by Po to obtain an actual value of a cylinder pressure ratio, CPR;
• (C) determining an optimum value of CPR for said compression ignition engine as a function of engine load and engine speed;
• (D) automatically adjusting at least one engine operating characteristic so as to vary air/fuel ratio, lambda, within the cylinder to cause said actual value of CPR approach said optimum value of CPR.