Patent GB-1244925-A (GB)
Title: Improvements in or relating to fuel feed devices for internal combustion engines
Inventor: MENNESSON ANDRE LOUIS
IPC: F02D41/36
Filed: 1969-09-25
Abstract: 1,244,925. Regulating I. C. engines. SOC. INDUSTRIELLE DE BREVETS ET D'ETUDES. Sept.25, 1969 [Oct.23, 1968; March 12, 1969], No.47193/69. Heading F1B. [Also in Divisions G1 and H3] In a fuel feed device for an I. C. engine, comprising at least one fuel valve openable by an electromagnet which is energized under the control of an energizing system adapted to be brought into operation simultaneously with the ignition system and to transmit, in synchronism with the rotation of a rotatable member drivable after the bringing into action of the ignition system, signals whose duration depends upon engine operating conditions, a signal being produced whenever the rotating member is in an angular position somewhere between two predetermined limits, at least one limit being variable, the energizing system comprises means adapted to interrupt transmission of a signal and thus to close the valve when the duration of the signal reaches a predetermined value. A rotating apertured disc 5 driven either by the engine or by an electric motor energized independently of the ignition switch 4 interrupts a beam of light from a bulb 8 to produce electrical pulses in a photo-cell 10, the distance of the bulb and cell from the spindle 7 of the disc being variable by means (such as those described in Specification 1,207,228) responsive to the rate of air-flow into the engine so as to vary the duration of the pulses. The pulses are fed via a timing circuit 33, a Darlington pair 15 and an output stage 20 to the electromagnet 2 of a fuel injection valve 1. If, while the engine is stationary with the disc 5 in a position in which the aperture 6 is between the bulb 8 and cell 10, the ignition switch 4 is closed but the engine starting control is not operated, the cell is continuously illuminated and provides a continuous signal for opening the injection valve 1. However, a capacitor 38 in the timing circuit 33 is then charged via a resistor 37 by the base current of a transistor 34 until the transistor is cut-off, whereby the injection valve 1 is re-closed after a time interval determined by the time constant of the capacitor and resistor. Further delivery of fuel while the engine is stationary is thereby prevented. During normal running, the tendency of the capacitor 38 to be progressively changed by the signal pulses is counteracted by discharging it after each pulse. For this purpose, the back e. m.f. generated in the electromagnet 2 when its current is abruptly decreased at the end of each signal pulse is applied via a Zener diode 44 whose Zener voltage is somewhere between the supply voltage and the back e.m.f. to the base of a transistor 41, causing the transistor to conduct and to discharge the capacitor via a resistor 47. If the engine is being rotated very slowly by its starter, the duration of each signal pulse may exceed the time taken to charge the capacitor 38 sufficiently to close the injection valve 1, whereby the injection valve is closed before the end of the signal pulse. This helps to prevent excessive fuel richness during cold starting. An alternative way of discharging the capacitor 38 after each signal pulse is afforded if the disc 5 is common to two or more devices similar to that shown in Fig.1, each device controlling a separate injection valve. In this case, the base of the discharging transistor 41 of each device is connected to a point between the Darlington pair 15 and output stage 20 of another device as that the transistor 41 is switched on by the signal pulses of the other device.