GB1333556A - Internal combustion engines - Google Patents

Abstract

1333556 Treating I.C. engine charge; fuel injection systems JOSEPH LUCAS (INDUSTRIES) Ltd 20 Nov 1970 [21 Nov 1969 26 Feb 1970] 57186/69 and 9472/70 Heading F1B [Also in Division G1] A valve for admitting air to the inlet manifold of an I.C. engine during over-run is operated by a solenoid 12, Fig. 2, which is energized from a circuit which comprises a trigger device 30, e.g., a contact assembly driven by the engine, which feeds trigger pulses at a rate proportional to engine speed to a diode pump 31 producing a D. C. voltage proportional to engine speed. This voltage is fed via an emitter follower 32 and a throttle switch 33 which is closed only when the engine throttle valve is closed, to a Schmitt trigger 34. An engine over-run, i.e., when the switch 33 is closed and the D.C. voltage is above a chosen level, the Schmitt trigger 34 operates a transistor switch 35 to energize the solenoid 12 and thereby open the air valve. The transistor switch 35 may be a monostable multi-vibrator in which the period of the unstable state is one or two seconds, so that the air valve is opened only for this period after the beginning of over-run. All the fuel injection valves may be opened simultaneously at the end of over-run to re-establish a film of fuel on the wall of the inlet manifold. For this purpose, a monostable multi-vibrator 36 is triggered by the Schmitt trigger so as to produce energizing pulses which are fed via amplifiers to the injector valves when the throttle switch 33 is re-opened or when the engine speed falls below the chosen level. Alternatively, in order that the multi-vibrator 36 is triggered only when the throttle switch 33 is reopened, it may be triggered either directly from the switch 33 or via a further Schmitt trigger having a triggering level corresponding to a lower engine speed, e.g., at or just below idling speed. Fig. 3 shows an arrangement in which two groups 41, 42 of electromagnetic fuel valves are operated during alternate periods of time by respective pulse generators 43, 44 which are triggered by respective trigger switches 49, 50 operated at a rate dependent on engine speed, the pulse duration being controlled as a function of engine speed and inlet manifold pressure by a signal V 1 and as a function of engine acceleration and engine water temperature by a signal V 2 . A control circuit 53 generally similar to that shown in Fig. 2 operates during over-run to cause admission of air to the inlet manifold and to provide outputs on leads 54, 55 to inhibit the outputs from the pulse generators 43, 44. When the throttle valve is opened after over-run or when the engine speed falls towards the idling speed, the circuit 53 provides output pulses on leads 56, 57 to energize both groups 41, 42 of injection valves simultaneously for a period of time determined by the duration of the unstable state of a monostable multi-vibrator forming a part of the circuit 53.