GB1363631A - Fuel injection system for internal combustion engines - Google Patents

Abstract

1363631 Regulating I C engine fuel injection PETROL INJECTION Ltd and H E JACKSON 26 May 1971 [26 May 1970 26 Feb 1971] 25304/70 and 5550/71 Heading F1B [Also in Division G1] The flow of fuel through at least one fuel injector 5 is controlled by a valve in or upstream of the injector which is opened for time periods determined by the rate of flow of a control fluid, e.g. air or fuel, through a line 13. A valve 21 controls flow through the line 13 in accordance with the position of an air valve 12 which is adjusted to maintain a substantially constant depression, e.g. 1 inch Hg, between the valves 11 and 12. The valve 12 may be eccentrically mounted for adjustment against closing spring bias or centrally mounted for adjustment by a servomotor (307), Fig. 8b (not shown) or as described in Specification 1254181. A switch 14 responsive to the fluid pressure in the line 13 has a contact 26 on a diaphragm 24, separating chambers 22 and 23, which engages a contact 28 to initiate either opening or closing of the fuel injection control valve and the moment of engagement is dependent on the rate of pressure change in the chamber 22. Fuel is supplied to the injector 5 by an electrically-driven gear pump 2 and the supply pressure is maintained substantially constant by a relief valve 6. In the embodiment shown, an electronic switching unit 8 produces a signal for simultaneously closing a solenoid valve (142), Fig. 3 (not shown) in each of four injectors 5 mounted in the respective engine intake passage for each two engine revolutions. Each injector 5 includes air inlets (150), Fig. 3 upstream of the injection orifice (148). The signal also closes a solenoid valve 15 at the inlet of the line 13 to atmosphere and air is drawn from the switch chamber 22 past the valve 21 into the region between the valves 11, 12. On engagement of the contacts 26, 28, which are normally biased open, the injector valves (142) and the valve 15 are opened. Closure of the injector valves and the valve 15 may be delayed by operation of a switch 212. The switch 212 may be operated by the valve 11, or a device responsive to the pressure downstream of the valve, when the valve is fully open. A screw (46), Fig. 5 (not shown) controls air-flow for idling into the intake passage 10 downstream of the valve 11. In another embodiment, Fig. 6 (not shown) the switch 14 is connected to the line 13 through a second solenoid valve (60) and the contacts 26, 28, which are normally biased closed, are opened when the second solenoid valve is opened. A signal from the switching unit 8 closes the second solenoid valve (60) and opens the injector valves and the valve 15. Air flows into the switch chamber 22 through the valve 15 and a restrictor (61), and when the contacts 26, 28 close the injector valves and the valve 15 are closed. A second signal from the unit 8 opens the second solenoid valve (60). In a further embodiment, Fig. 7 (not shown) the valve 21 controls fuel flow from the pump 2 through a control line (80) to the supply tank 1 and a pressure switch (72) in the line has contacts 26, 28 which are moved apart when a second solenoid valve (60) is opened and begins to close when the second solenoid valve is closed and the valve 15 is opened to allow fuel flow from the switch chamber 22 back to the supply tank 1 through a restrictor (61). In this embodiment the fuel pressure in the control line (80) is set by a valve (75) in accordance with the depression between the valves 11, 12. When the depression momentarily increases as the throttle valve opens the control line pressure increases and thus the injection duration increases. In a final embodiment, Figs. 8a, 8b, 8c and 9 (not shown) the valve 12 is positioned by a servomotor (307) operated by the depression between the valves 11, 12. The servomotor (307) operates through a cam and a follower (318, 319), Fig. 8b, on an air metering valve, e.g. a rotatable valve as described in Specification 1098821, in the air line 13. In this embodiment, with the injector valves and the valve 15 closed, air is drawn from the switch chamber 22 through the air metering valve and the contacts are drawn apart. A signal from the unit 8 opens the injector valves and the valve 15 and air flows into the chamber 22 through a restrictor (13a) until the contacts 26, 28 close and the injector valves and valve 15 are closed. To compensate for transient changes in the depression between the valves 11, 12 the switch chamber 23, which is connected to atmosphere through a restrictor (301), is connected to the region between the valve 11, 12 by a line (300) also containing a restrictor. The switch chamber 23 is also connectible to atmosphere through a manually-operable valve (330) to provide extra fuel for starting. A by-pass (334) connecting the intake conduit 10 upstream and downstream of the valve 11 is opened simultaneously by a valve (331). The chamber 23 may also be connected to atmosphere by a valve (304), Fig. 8a, or (360), Fig. 10 (not shown) operated by intake manifold pressure on acceleration. To cut off the operation of the injector valves on overrunning a switch (393), Fig. 8a, opens at high manifold vacuum. A single solenoid valve may control fuel flow to a plurality of pressure responsive injector valves. The unit 8 may produce signals at a constant frequency.