GB927887A - Fuel-injection pumps for internal combustion engines - Google Patents

Abstract

927,887. Fuel distributing valves; fuel injection engines. S.U. CARBURETTER CO. Ltd. Jan. 5, 1962 [Aug. 12, 1961], No. 29202/61. Classes 7(3) and 7(6). In a liquid-fuel metering pump for fuelinjection I.C. engines of the type in which that portion of the total charge which, at the moment of ignition, resides in the neighbourhood of the ignition means, is maintained in a readily combustible state in respect to its fuel/air ratio, whereas the remainder of the charge may be of substantially lower fuel/ air ratio, at least two distensible metering chambers of individually adjustable volumetric capacity are charged periodically, under the control of a distributing valve, with pressurized liquid-fuel and, at recurrent intervals, by spring loading or fluid pressure, each chamber is caused to abruptly contract and thereby rapidly eject its fuel content to one. of two delivery outlets which respectively serve separate pilot injection and main injection nozzles supplying one and the same cylinder of the engine. The distributing valve may be a simple rotary valve. Alternately, as shown, it comprises a disc valve 8 provided with alternating ports V 1 , V 2 and having teeth 11 on its periphery, and it is caused to move in epicyclic motion around a ring gear 12 by an eccentric 13 fixed to a rotating shaft 14. The valve 8 is maintained in continuous contact with surfaces 9, 10 by a spring 20 situated between a cover 5 and a distributing head 2 mounted on a resilient diaphragm 4. The head 2 may be mounted on other resilient means such as an O-ring seal disposed in a groove between the periphery of the head 2 and the wall of the surrounding casing. The head 2 has ports d 1 , d 2 which connect with conduits 36, 38 leading to pilot injection nozzles n 1 , n 2 , and has ports D 1 , D 2 which connect with conduits 35, 37 leading to main injection nozzles N 1 , N 2 . A pump 15 having a by-pass relief valve 16 supplies pressurized liquid fuel through an inlet 17 into a crescent shaped chamber 19 around the valve 8. When the valve 8 uncovers ports 31, 32 in a block 1, fuel from the chamber 19 passes through conduits 27, 28 to auxiliary and main metering chambers m 1 and M 2 respectively, and pistons 21, 23 are forced down against springs 22, 24 on to stops 41, 43 adjustable by cams 40, 42. At the same time, the valve 8 interconnects, generally sequentially, ports 33, 34 with d 2 , D 2 so that pistons 21, 23 in chambers m 2 , M, are forced upwardly by their springs 22, 24 to expel fuel through conduits 29, 30 ports V 2 , V 1 , and d 2 , D 2 , and conduits 38, 37 to nozzles n 2 , N 2 situated in one engine cylinder, or induction port, or in both these locations. A rod 44 interconnects cams 40, 42 for the purpose of varying the quantity of injected fuel. A duct 25 vents the rear of the metering chambers to the suction of the pump 15. The fuel metering pump may be arranged to supply more than two cylinders. Each pilot nozzle may be situated in a pre-combustion chamber arranged symmetrically at the top of the main combustion chamber of an engine cylinder, the corresponding main nozzle being situated in the inlet conduit just upstream of the inlet valve. In a modification (not shown) only one auxiliary metering chamber and one main metering chamber are provided for every two engine cylinders, and the free pistons in each metering chamber expel fuel to one cylinder on their upstrokes and to the other cylinder on their downstrokes; the force to expel fuel at one side of each piston being provided by the incoming pressurized fuel at the other side, instead of being provided by springs. Desirably, provision is made to automatically regulate the maximum fuel delivery to the engine per cycle in accordance with the ambient air temperature and barometric pressure. Specification 708,592 is referred to.