Controlled variable compression ratio internal combustion engine

Abstract

An improved arrangement for controlling and adjusting the compression ratio of an internal combustion engine (10) during operation. A secondary cylinder (201) is formed in the engine cylinder head (102) and opens upon the combustion chamber (110) of the engine. A secondary piston (203) is positioned by a control device (503) within the secondary cylinder (201). The rear most position corresponding to the lowest compression ratio. The desired position of the secondary piston (203), that compression ratio which corresponds to maximum efficiency of the engine, is controlled by a logic unit (816) operating upon such inputs as the engine load as correlated to the input manifold pressure, the engine RPM and the present position of the secondary piston (203). The linkage of the control may utilize a servo motor or hydraulic driver to rotate a shaft (301). All secondary pistons (203) may be operated in unison or a control system may be provided for each cylinder (201). An involute surface (302) mounted on the shaft (301) pushes the spring (204) loaded secondary piston (203) into the secondary cylinder (201). A worm gear (602) on the shaft (301) may turn a threaded bolt (603) to position the secondary piston (203). Or, a worm gear (813) may engage a gear (814) formed on the involute (815) to directly position the involute surface (815).