Automatic ignition timing mechanism for I.C. engine - has disc with two groups of timing holes driven by engine

摘要

An opaque disc (1) is driven by the engine at a speed corresponding to engine speed. Holes (2, 3) round its circumference are separated into two groups (10, 11). The edge of the disc passes between a light (4) and a photoelectric cell so that pulse is generated every time a hole passes under the light. The interval between the last hole of one group and the first hole of the second group at maximum speed is greater than the interval between successive holes of the same group at minimum speed. The generated electrical impulses are fed to a digital electronic circuit which controls ignition timing to two groups of cylinders.