GB1458731A - Ignition apparatus for internal combustion engine - Google Patents

Abstract

1458731 Ignition systems HITACHI Ltd 10 April 1974 [13 April 1973 8 Aug 1973] 15969/74 Heading FIB Ignition control apparatus for an I.C. engine comprises a rotor 1, Fig. 1, rotating with the engine crank-shaft, and a pick-up 2 generating a rotational angle signal as shown in (a) Fig. 3, a first delay signal generator produces a delay signal lagging by a predetermined time T, and fed to a measuring circuit 4 measuring the time interval from the end of the delay pulse by a predetermined coefficient m, and producing an output signal measuring a time interval by a predetermined coefficient m 2 from the rotational angle pulse, a comparator 5 producing an output signal as in (d), Fig. 3, when the output from 4 reaches a predetermined level R, the output from a second time delay signal generator, being de-energized after the lapse of a predetermined time T 2 ' as shown in (d'). The output (d) from the comparator 5 may be applied to the switching diode (115), Fig. 2A (not shown), of a known capacitor discharge ignition system. Alternatively, in a known induction type ignition circuit, the output of the second time delay signal generator 6, (d'), is used to de-energize a switch (210), Fig. 2B (not shown), previously energized by the output of comparator 5. Again, sufficiently high ignition spark energy is maintained even in the case of an excessive voltage drop of the battery power supply by inserting a first time interval generator (8), Fig. 6 (not shown), between the generator 3 and measuring circuit 4 generating a signal corresponding to variation of the voltage across the battery. A second variable time interval generator (9) replaces the second time delay signal generator 6. Again, Fig. 10, a rise of the pick-up signal from 13 acts to trigger a signal from a first variable time interval generator 14 of a width dependent on the magnitude of the battery voltage. A first constant current circuit 15 operates from the fall of the generator 14 output signal to the fall of the pickup signal to linearly charge a capacitor 16. The capacitor 16 then linearly discharges through a second constant current circuit 17. When the voltage across the capacitor is reduced to zero, a second variable time interval generator 18 is triggered to produce pulses of a width in response to the voltage across the battery, the output of the generator 18 being applied to the base of a transistor 19 to make it conduct to control the ignition coil 20. Particular circuit diagrams are provided for the various embodiments, as are digital applications of the circuits, Figs. 5, 9 and 13 (not shown).