GB1428209A - Ignition systems for internal combustion engines - Google Patents

Abstract

1428209 Timing ignition ROBERT BOSCH GmbH 6 June 1973 [7 June 1972] 26973/73 Heading F1B Two-stage retardation of the ignition timing of an I.C. engine is effected by a vacuum servo 40 acting through a diaphragm 29 and a rod 15 on a breaker plate 11 to move the rod initially a distance a against a first spring 19 until a nut 41 on the rod abuts a spring-loaded stop body 17 which, for the second stage movement, is itself moved a distance b until the end 48 of the rod abuts a stop screw 52. The first stage corresponds to idling operation of the engine, or low speed engine braking, and the second stage to high speed engine braking and rapid heating-up of exhaust gas aftertreatment devices. As shown, an annular vacuum chamber 43 moves the stop body 17 during second stage retardation. The vacuum servos 40, 43 are connected to the inlet manifold by valves responsive to the carburetter butterfly valve position and engine speed or exhaust gas aftertreatment device temperature respectively, a vacuum being applied to the chamber 40 whenever it is applied to the chamber 43. Again, Fig. 2 (not shown), an ignition advance chamber (53), connected to the inlet manifold under part-load engine operating conditions, is provided on the opposite side of diaphragm 29. Also, Fig. 3, (not shown), the first retard chamber 40 is formed as the annular chamber, and the retard chamber 43 is partially defined by the diaphragm 29. Again, Fig. 4, (not shown), the second retard chamber is replaced by an electromagnet (86), and Fig. 5 (not shown), an advance vacuum chamber (53) is provided.