Controlled compression internal combustion engine having fluid pressure extensible connecting rod

Claim 1

In an internal combustion engine which includes: a combustion cylinder into which combustible gases may be introduced, compressed and burned; an engine piston in said cylinder; a crankshaft having a throw journal and an oil passage which includes an outlet port opening radially outwardly of said throw journal; pump and valve means connected to supply oil under regulated pressure to the oil passage of said crankshaft; and a variable length connecting rod including relatively extensible and retractable sections connected between said piston and the throw journal of said crankshaft and defining in said connecting rod a plurality of relatively communicating hydraulic pressure chambers into which oil under pressure may be introduced to lengthen said connecting rod and from which oil may be discharged to shorten said connecting rod; that improvement which comprises: (a) an inlet-outlet passage in said connecting rod in continuous communication with said hydraulic pressure chambers and arranged to communicate with the oil outlet port of the throw journal of said crankshaft only when the throw journal occupies a position slightly in advance of a top dead center position, said connecting rod closing the oil outlet port of the throw journal in all other rotative positions of the throw journal; and (b) dash pot means in said connecting rod arranged to retard the relative extension of the sections of said connecting rod while permitting free retraction thereof.