Method of and apparatus for starting an air-compressing four-stroke cycle internal combustion engine

Claim 1

In an internal combustion engine having a crank shaft and an axially stationary cam shaft having cams thereon, the cam shaft being rotated by the crank shaft at one-half the speed of the crank shaft, and the engine further having spring-biased, normal-closed intake and exhaust valves opened periodically by rocker arms displaced periodically by the cams on the cam shaft, the improvement characterized by: the cams being grouped in pairs on the cam shaft with the cams in each pair being axially juxtaposed with respect to one another and having single lobes which are circumferentially displaced from one another; a single rocker arm positioned between each pair of cams and each of the valves, the single rocker arm having a cam follower surface of a sufficient width to engage simultaneously both cams in the pair; means for rotatably mounting the rocker arm, wherein the rocker arm pivots to open the valve against the bias of the valve spring as the lobes engage the cam follower, said mounting means further including means allowing the rocker arm to slide in an axial direction with respect to the cam shaft; means for limiting sliding motion of the rocker arm between a first position in which the cam follower abuts both cams of the pair and a second position in which the cam follower abuts only one of the cams; means for biasing the rocker arm to the first position wherein the cam follower engages both cams and the engine functions initially as an air pump during starting of the engine, and means for overcoming the biasing means to urge the rocker arm to the second position in which the cam follower engages only one cam wherein the engine runs as a four-cycle engine, said means for overcoming the biasing means operating automatically upon self-sustaining operation of the engine.