Decompression device for four-stroke engine

Abstract

A decompression device for a four-stroke engine, which drives the inlet valve and the exhaust valve by using the profile surface of a cam and rocker mechanism. This cam includes a guiding recess provided on the side surface thereof and a slot provided on the cam profile surface communicating with the guiding recess. The decompression device further includes a centrifugal member, received within the guiding recess, having a projecting portion and being rotatable and movable within the guiding recess, and a spring having two ends fixed to the cam and the centrifugal member. By the cooperation with the spring and the guiding recess, when the cam is rotated at a lower speed, the projecting portion of the centrifugal member projects through the slot to the outside of the cam profile surface under the action of a weaker centrifugal force, thereby lifting the second follower so as to open the exhaust valve before the TDC of the compression stroke, and when the cam is rotated at a higher speed, the projecting portion of the centrifugal member sinks into the inside of the cam profile surface under the action of a stronger centrifugal force, thereby closing the exhaust valve.

Claims aren’t available for this document.