Emission control system for a crankcase-scavenged two-stroke engine operating near idle.

摘要

An engine control system is disclosed for reducing the hydrocarbon content in exhaust gas from a crankcase-scavenged, two-stroke engine (10) in the operating range near idle, with light operator-induced engine loading. As operator demand for engine output power is increased, the control system increases the fuel per cylinder delivered to the engine (10), whilst restricting the supplied mass of air per cylinder to a value less than or equal to that flowing at unloaded engine idle, in said operating range. This is done by coupling a throttle pedal (56) to a throttle valve (52) in an air intake manifold (20) through a pivoted linkage system (60,62,64,66,68,70,72,74) which includes a lost-motion connection (72,74), which prevents movement of the throttle valve (52) until a predetermined displacement of the throttle pedal (56) has occurred. A computer (48) of the control system controls the fuel supply per cylinder in response to signals (PED) received from a potentiometer (84) monitoring all mobement of the throttle pedal (56). The control system also may include an air bypass passage (76) and a computer-controlled, solenoid-actuated valve (78) to further control the supplied mass of air in said operating range.