GB1262089A - Fuel injection systems - Google Patents

Abstract

1,262,089. Regulating I. C. engines. C.A.V. Ltd. Aug.26, 1969 [Sept.6, 1968; Dec.2, 1968], Nos. 42497/68 and 57039/68. Heading F1B. In a fuel injection system for an I. C. engine, high pressure fuel from an accumulator 15, Fig. 1, supplied by a pump 16, is supplied to a conduit 14 when a valve 17, operable in synchronism with the engine, is opened. The high-pressure fuel moves a stepped metering shuttle 26 towards the small end of associated cylinder 27 against accumulator pressure communicated through conduit 18, the stroke of the shuttle being manually adjustable via an adjustment member 30a. The valve 17 is then closed, whereafter a timing valve 19, movable in synchronism with the engine via mechanical or electrical means, e.g. a solenoid, is moved into a position in which it communicates a low-pressure conduit 21 with the chamber above an injector valve 12. Thus the injector valve is opened by the pressure of the fuel in conduit 14 and allows the fuel to flow to an engine combustion chamber via orifices 11. Consequent return of the shuttle 26 communicates ports 28, 30 and relieves the pressure in conduit 14 via restrictor 29 and conduit 21, thereby causing the injector valve 12 to close. The timing valve eventually moves back to the position shown to communicate accumulator pressure with the chamber above the injector valve. The pressure in the conduit 21 is maintained at a fixed proportion of that in conduit 18 by a spill valve 23 associated with a drain port 24. The valve 12 may instead control the flow of fuel to a conduit leading to an injector (33) Fig. 2 (not shown). In Fig. 3 (not shown), the restrictor 29 is replaced by a valve (34) which is closed when the valve (17) is open, and the chamber above the injector valve is connected to a portion of conduit (18) isolated by a restrictor (35), which conduit portion is periodically communicated to an outlet via a solenoid-actuated valve (40) to create a flow in conduit (18) and thereby a lowering of the pressure in the conduit portion to cause the injector valve to open. In another embodiment, Fig. 4 (not shown), the injector valve (46) is held closed via a push rod by a piston (49) subjected to the pressure in conduit (18), but opens when the closing forces exerted on the injector valve are periodically reduced by a solenoid (51) mounted about the push rod.