Internally cooled high compression lean-burning internal combustion engine

Abstract

An internally cooled internal combustion piston engine and method of operating a piston engine is provided, with the combination of liquid water injection, higher compression ratios than conventional engines, and leaner air fuel mixtures than conventional engines. The effective compression ratio of the engines herein is greater than 13:1. The engines may employ gasoline or natural gas and use spark ignition, or the engines may employ a diesel-type fuel and use compression ignition. The liquid water injection provides internal cooling, reducing or eliminating the heat rejection to the radiator, reduces engine knock, and reduces NOx emissions. The method of engine operation using internal cooling with liquid water injection, high compression ratio and lean air fuel mixture allow for more complete and efficient combustion and therefore better thermal efficiency as compared to conventional engines.

1 - 25 . (canceled) 
     
     
         26 . An internal combustion engine for use with a hydrocarbon fuel with at least one cylinder and a reciprocating piston therein, an inlet manifold with at least one air intake valve, an exhaust manifold, at least one exhaust valve in fluid communication with said exhaust manifold, and a fuel handling system with at least one fuel injector, said engine comprising:
 a water injector coupled to a water source for injecting liquid water into the cylinder from about 180° to about 30° before Top Dead Center (TDC) of said piston during a compression stroke, wherein the amount of water injected is greater than the amount of water that is present at the saturation point of water vapor in the ambient air in the cylinder;   a turbocharger or supercharger that adjustably modulates the quantity of air forced into the intake manifold or cylinder;   a pressure sensor in the cylinder, and one or more temperature sensors selected from the group consisting of temperature sensor in the cylinder, temperature sensor in the exhaust manifold, temperature sensor in the inlet manifold, and any combination thereof; wherein said sensors are coupled to a control device that receives sensed pressure and temperature sensors values and adjusts the amounts of water injected and air to fuel ratio provided to the said at least one cylinder;   
       wherein a ratio of air to fuel provided to said at least one cylinder is greater than stiochiometric, and the engine has an effective compression ratio greater than 13:1.