GB1193337A - Improvements in or relating to Internal Combustion Engines - Google Patents

Abstract

1,193,337. Transistor pulse circuits. ROBERT BOSCH G.m.b.H. 22 Aug., 1967 [24 Aug., 1966], No. 38528/67. Heading H3T. [Also in Division G1] The output of a monostable circuit KG, Fig. 1, in an I.C. engine injection control system, is fed to a circuit ST which shortens the pulse width of the monostable output by delaying the leading edge. The pulses from the circuit ST are made to start later than the monostable output pulses (T N , T G , Fig. 2, not shown) and to finish simultaneously, whereby a given variation in pulse width of the monostable output by resistor 34, connected to the inlet manifold pressure transducer 35, represents a larger proportional variation of the reduced width output of circuit ST. The monostable comprises a normally ON transistor T1 and a normally OFF transistor T2, a pulse from a cam-controlled switch A changing over the states of these transistors to apply a positive pulse to a capacitor 41 in circuit ST and a negative pulse to a resistor 40. Since the right hand plate of capacitor 41 is already positively charged through diode 43, the base of transistor T3 is taken even more positive, holding it cut off, until the positive voltage decays through resistor 40 to the point where T3 conducts. This represents the start of pulse (TN). In other embodiments, an NPN transistor is used in circuit ST (T4, Fig. 3, not shown), an NPN transistor replaces T2 (T5, Fig. 4, not shown), and a variable inductance transformer is used in the monostable KG as the pulse width varying device (Fig. 5, not shown).