Timer means for sequential fuel injection

Abstract

Abstract 1440346 Electronic fuel injection control systems INTERNATIONAL HARVESTER CO 14 June 1973 [21 June 1972] 28300/73 Heading G3N In an I.C. engine electronic fuel injection system in which a plurality of injection valves are actuated in sequence in synchronism with intake strokes of the engine, the duration of actuation of each valve is controlled by a timer circuit triggered in predetermined phase relationship to intake strokes of the engine and controlled by two control voltage, dependent respectively on engine speed and intake manifold pressure, so as to develop, upon each triggering, an output signal after a time interval, during which a valve is actuated, having a duration which is a linear function of each of the control voltages and thus a linear function of their product. In accordance with the invention, the timer circuit, for example as shown in Fig. 5, includes a capacitor 200, a source of regulated voltage 204, a transistor 202 responsive to each triggering signal for coupling the capacitor 200 to the voltage source 204 to fix the voltage across the capacitor at a value substantially equal to the regulated voltage, a controllable current sink 210 connected in parallel with capacitor 200 and operative to discharge the capacitor at a linear rate controlled by the magnitude of one of the control voltages, and a trigger circuit 218 which is triggered from one state to another to develop said output signal when the voltage across the capacitor reaches a level controlled by the magnitude of the other control voltage. The fuel injection system described with reference to Figs. 1 and 2 (not shown) is substantially as described in application number 28298/73 and includes a timer circuit in accordance with the present invention. As shown in Fig. 3, eight injection valves 121- 128 are provided, the valves being actuated in a sequence determined by a circuit 149 and for a duration determined by four timer circuits 151- 154 connected to NAND gates 141-148 as shown. Each timer has two inputs, one receiving a control voltage on line 159 dependent upon engine speed derived from a tachometer 162 and a conditioning circuit 161, and the other receiving a control voltage on line 160 dependent upon intake manifold pressure derived from a circuit 164 and a conditioning circuit 163. Each timer may be constructed as shown in Fig. 5. As further shown in Fig. 3, a switch 165 is connected to be closed when the throttle is wide open to provide fuel enrichment, and a switch 168 is connected to be closed when the throttle is closed to operate a fuel inhibit circuit 167.

Inventors

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