A fourcycle, free piston, premixed charge, compression ignition, internal combustion reciprocating piston engine with a variable piston stroke comprising:
- four cylinders constructed in a manner typical of reciprocating engines, each of said cylinders having two open ends;
- at least one cylinder head affixed to said cylinders and configured to close one of said open ends of each said cylinder;
- four pistons, each associated with and positioned for free movement within a different one of said cylinders;
- two of said pistons coupled by a first mechanism to form a first piston pair so as to reciprocate together and the other two of said pistons coupled by a second mechanism to form a second piston pair so as to reciprocate together;
- means of causing said first piston pair to reciprocate together, and said second piston pair to reciprocate together, all without a predetermined stroke length, and in a manner that allows a variable stroke and variable compression ratio, and wherein said reciprocation together of the said second piston pair is selected from a group consisting of reciprocation in the opposite direction to said first piston pair and reciprocation in the same direction as said first piston pair;
- means of forming a premixed charge of fuel and reactant, said means of forming comprising means of controlling the size of said premixed charge and means of controlling the composition of said charge;
- at least one intake valve associated with each of said cylinders which is configured to control the introduction of said premixed charge into the associated one of said cylinders;
- means of conducting said premixed charge of fuel and reactant to each of said at least one intake valves;
- said pistons each configured and dimensioned to create an intake stroke within an associated one of said cylinders wherein reciprocating motion of said piston away from said cylinder head allows said premixed charge to travel through said at least one intake valve and into the one of said cylinders associated therewith;
- a combustion chamber formed within each of said cylinders, each said combustion chamber defined by said piston, the associated one of said cylinders, and said at least one cylinder head closing said cylinder;
- said pistons each configured and dimensioned to also create a compression stroke within an associated one of said cylinders wherein reciprocating motion of said piston toward said at least one cylinder head continues until said piston compresses said premixed charge in said combustion chamber sufficiently to raise the temperature of said premixed charge to cause autoignition of said premixed charge and form combusted gases;
- said pistons each configured and dimensioned to further create an expansion stroke within an associated one of said cylinders into which said piston is positioned for free movement wherein reciprocating motion of said pistons away from said at least one cylinder head allows said combusted gases in said combustion chamber to expand;
- said at least one exhaust valve associated with each of said cylinders and configured to control the discharging of said combusted gases from said cylinder;
- said pistons each configured and dimensioned to create an exhaust stroke within an associated one of said cylinders into which said piston is positioned for free movement wherein reciprocating motion of said piston toward said at least one cylinder head allows said expanded combustion gases to be exhausted through at least one said associated exhaust valve;
- means of conducting said combustion gases as exhaust from said engine;
- means for controlling the timing and causing of said intake valves and said exhaust valves to open and close during all of said cycles;
- means of providing lubrication of said engine;
- closure means adapted for sufficiently closing so as to contain lubricants and gas leakage past said pistons the one of said open ends of each said cylinder not closed by said at least one cylinder head;
- means for starting said engine;
- and
- means of providing cooling of said engine.