Combustion chamber for internal combustion engine and process of combustion using fuel radical species

In a piston for a reciprocating piston internal combustion engine in which a combustion cycle is carried out in a variable volume combustion chamber defined by the piston reciprocating in a close ended cylinder into which a fuel and air charge is periodically supplied, and which cycle includes intake, compression, combustion, expansion and exhaust portions, and wherein the piston crown includes a recess that contains the majority of the charge when the combustion chamber is at minimum volume, the improvement comprising:

• said piston including at least one reaction chamber having a curvilinear sidewall in cross-section disposed in the piston crown area adjacent the periphery of the recess, and an array of discrete orifices providing the sole communication between the recess and the reaction chamber, said reaction chamber and orifices being shaped and dimensioned such that during the compression part of each combustion cycle, a portion of the charge is admitted into the reaction chamber through the orifices with the flow of any gaseous portion of the charge being choked during at least part of the compression event;
• the charge admitted to the reaction chamber is radially vortically swirled in intimate contact with the sidewall of the reaction chamber, so as to effect heat transfer to the admitted charge and its partial oxidation reaction to create radical species of the fuel;
• any flame front approaching the reaction chamber from the combustion chamber is quenched;
• and outward flow of compressible gas with radicals from the reaction chamber into the combustion chamber through the orifices is choked during at least part of the expansion and exhaust portions of each combustion cycle;
• and radicals of the fuel are produced and retained temporarily in the reaction chamber during the combustion, expansion and exhaust portions of a combustion cycle and are discharged into the piston recess following the conclusion of the exhaust portion at least in advance of the compression portion of the succeeding combustion cycle in Sufficient quantity to condition the next succeeding charge in the combustion chamber for preselected ignition and combustion characteristics.

A process of radical seeding of a charge in a combustion chamber of an air breathing reciprocating piston type internal combustion engine including a piston having a recess area at its crown area defining the major part of the combustion chamber volume at the minimum volume condition, and a fuel supply system arranged to supply fuel into the combustion chamber to carry out a combustion cycle including intake, compression, combustion, expansion and exhaust portions comprising:

• providing a reaction chamber having a curvilinear chamber sidewall in cross section in the piston crown area adjacent the periphery of the recess and extending at least part way around the outer periphery of the recess area;
• providing an array of discrete orifice including at least one fuel control orifice and at least one air control orifice, said array of discrete orifices providing the sole communication between the reaction chamber and the recess area with at least one orifice intersecting said curvilinear chamber sidewall tangentially so that a radial vortical flow is induced in the reaction chamber when fluid flow is induced in the reaction chamber from the recess area through said one orifice during each compression stroke of the piston;
• directing fuel of each charge during each combustion cycle to said at least one fuel control orifice and controlling the admission of primarily fuel to the reaction chamber through said fuel control orifice, and utilizing said at least one air control orifice which is spatially separated from the fuel control orifice to control the admission of primarily air into the reaction chamber;
• selecting orifice dimensions, configuration and location such that combustion flames from the combustion chamber are quenched by the orifices before they can extend into the reaction chamber and such that inflow and outflow of compressible gases to and from the reaction chamber from and to the recess area are choked due to differential pressure conditions existing across the orifices during part of the expansion, exhaust and compression portions of each combustion cycle, so that the pressure fluctuations in the reaction chamber always lag behind the pressure fluctuations in the combustion chamber and so that radicals generated in the reaction chamber during a combustion cycle are partially retained in the reaction chamber during the combustion, expansion and exhaust portions of the combustion cycle and are partially discharged into the recess area near the start of the compression portion of the succeeding combustion cycle;
• carrying out each combustion cycle by directing at least a portion of the fuel charge for each cycle into the reaction chamber and partially cool flame oxidizing the charge in the reaction chamber to generate radical fuel species while the charge is vortically swirled in intimate contact with the chamber sidewalls, and by discharging a portion of the radicals generated in the reaction chamber into the recess through said orifice array under said choked outflow conditions;
• carrying out the generation of radicals in the reaction chamber and controlling the generation of radicals within the reaction chamber in accordance with the formula:
• R.sub.OUT =R.sub.GEN. +R.sub.IN -R.sub.RET. .gtoreq.R.sub.CRIT.
• where:
• R.sub.OUT =radicals discharged from the reaction chamber into the piston recess area;
• R.sub.GEN. =radicals generated during each combustion cycle in the reaction chamber;
• R.sub.IN =seeded radicals returned to the reaction chamber from the combustion chamber during compression of a charge;
• R.sub.RET. =radicals retained in the reaction chamber;
• R.sub.CRIT =the minimum quantity of radical species of fuel in the reaction chamber required to obtain preselected ignition and combustion characteristics of the charge each combustion cycle.