Ignition advance for controlling polluting emissions from IC engine - has vacuum inlet ducts upstream and downstream of throttle and engine temp. sensor to advance mechanism

摘要

A pneumatic actuator (A) provides variation in the angle of advance of the ignition and has a barometric or vacuum chamber (S) which communicates via a selectively switchable solenoid valve (4) with a choke tube (D) of the carburettor (C) at the inlet duct opening (3) downstream of a main throttle valve (V). A one-way flow-valve (5) has the purpose of keeping the vacuum within the chamber after it has been created by the suction action exerted through a pneumatic line (2). Upstream of the throttle valve, a second inlet duct (9) connects via pneumatic line (8) with a delay valve (10) in parallel with the solenoid valve (11). The electrical control circuit (12) responding to engine oil temp. sensor (14) switches the solenoid valves. The operation of which is associated with the choke (W) such that the vacuum advance is delayed until a threshold engine temp. is reached.