GB1329630A - Internal combustion engine fuel control system - Google Patents

Abstract

1329630 Fuel injection systems for I.C. engines BENDIX CORP 22 Dec 1971 [28 Dec 1970] 59561/71 Heading G1N In an I.C. engine intermittant fuel injection system, a signal having a magnitude related to intake manifold pressure is compared with a pulse train which has a pulse duration related to engine r.p.m. and a pulse magnitude which varies in a predetermined manner to provide injection valve actuating pulses synchronized with engine rotation and having duration which vary with engine speed and intake manifold pressure. There is shown a system for controlling two groups of injection valves. A signal from an engine speed transducer 3 is applied to a pulse forming network 30 which provides pulse trains TR1, TR2 Á 1 and Á 2 in Fig. 3 to a switching network 20 and a delay pulse network 50. During the period T1 of the pulses TR1, the network 20 allows a charging current I 1 , from circuitry 10, to charge a capacitor C1, in a network 40, and a charging current I 2 to charge a capacitor C2, and during the periods T2 of the pulses TR2, I 2 to charge C1 and I 1 to charge C2 so as to provide capacitor voltages as shown by Á 5 and Á 6 in Fig. 3. The delay pulses P1, P2 cause a delay in charging by current I 1 (portion AB and A<SP>1</SP> B<SP>1</SP>), and I 1 is such that capacitor C1 or C2 is fully charged when the voltage reaches point C or C<SP>1</SP> Current I 2 causes capacitor Cl and C2 to charge in a linear manner (portion DE or D<SP>1</SP> E<SP>1</SP>). A switching network 60 passes the voltage appearing on capacitor C2 during the periods T1 and that appearing on capacitor C1 during the periods T2 to a comparator 80 to which the manifold pressure signal is also applied, which forms a reference voltage (points F and F<SP>1</SP>). Each injection valve actuating pulse in then generated between the portions DF and D<SP>1</SP> F<SP>1</SP>. (Á 8 and Á 9 in Fig.3). As shown in Fig.3, as the engine speed increases for a constant manifold pressure the points D and D<SP>1</SP> approach the points C and C<SP>1</SP> respectively, and it is only when the points D and D<SP>1</SP> are initiated on the portions BC and B<SP>1</SP> C<SP>1</SP> respectively that the injection valve actuation pulse duration increases due to the increased time between the points D and F, and D<SP>1</SP> and F<SP>1</SP> respectively. In actual practice, the manifold pressure would also change and thus vary the positions of points F and F<SP>1</SP> and thereby the injection pulse duration. Fig.7 (not shown), shows details of the circuits 10, 20, 40, 60 and 80. The characteristics of the capacitor voltages may be varied as desired, e.g. the portions BC and B<SP>1</SP> C<SP>1</SP> may be non-linear or the slope of portions DE and D<SP>1</SP> E<SP>1</SP> may be different, Fig.6 (not shown).