GB1045925A - Fuel supply system for compression ignition internal combustion engines - Google Patents

Abstract

1,045,925. Regulating I.C. engines. C. L. CUMMINS. June 3, 1964 [July 2, 1963], No. 23045/64 Addition to 973,769. Heading F1B. The fuel supply system in the parent Specification is modified to control the fuel supply in conditions of idling, coasting, acceleration and overspeed and to prevent overfuelling when used in a supercharged engine. Figs. 1, 2. An engine-driven pump 24 draws fuel from tank 20 through a filter 22 and delivers it through conduit 25, filter 26, solenoid-operated shut off valve 35 and conduit 36 to port 37. Spill-off from pressure regulator 28 is returned to the pump suction. Pressurized fuel passes through conduit 44 in a rotor 38 driven by the engine through gears 70, 71 and through port 45, conduit 46 to chamber 47. Piston 32 moves to expel fuel from chamber 52 through conduit 53, port 50, conduit 48, rotor groove 51, conduit 54, passage 55 in throttle shaft 56, conduits 57, 58 groove 60 in an engine-driven rotor 41, passage 61, port 62 and conduit 63 to chamber 65 in injectors 33. When rotor 38 is turned through 180 degrees pressurized fuel is directed to chamber 52 and fuel expelled from chamber 47 is directed to the next injector 33 by rotor 41. The same rotor 38 can be used for a four, six, eight or twelve cylinder engine with a modified distributer 64. Cam groove 72 on throttle shaft 56 controls the swept volume of chambers 47, 52. Idling speed and coasting fuel shut off. When the engine is at rest, rotor 38 is forced to the left and passage 55 does not connect ports 77, 78. During starting fuel pumped by piston 32 passes from port 80 to throttle by-pass conduit 81 until increasing engine speed causes governoractuated movement of the rotor 38 to the right to partially close port 80 by shoulder 82 until an equilibrium position is reached corresponding to the idling fuel requirements. With the throttle 56 closed and the engine running above idling speed port 80 is closed, fuel pressure is available for acceleration at port 77 and piston 32 is hydrostatically locked. Overspeed and "Runaway" control. Above a predetermined engine speed ports 84, 85 are uncovered so that part of the fuel charge passes through port 85 and conduits 86, 23 to the fuel pump suction side. At the same speed conduit 44 begins to pass out of alignment with port 37 to cut off the fuel supply to chambers 47, 52. In the case of a fuel supply failure air in conduit 58 is sucked through conduit 81, port 84 and conduit 86 to eliminate the "pneumatic ram" effect. Acceleration fuel supply. When the engine is in the intermediate speed range and the throttle shaft 56, Fig. 6 (not shown), is rotated to 90% of its fully open position, passage 93 begins to connect ports 94 and 95 so that approx. 5% excess fuel is supplied for acceleration through port 37, passage 44, passages 102, 87, torquerise flow adjusting valve 100, passage 88, port 97, groove 96, port 98, passage 90, port 94, passage 93, port 95 and passage 58. In a further embodiment the excess fuel for acceleration may be supplied from a second metering piston or the first metering piston may have a shaped spool cam surface. The valve 100 may be locked at a desired setting in its own housing 101 before assembly or in a modification it may be housed in the throttle shaft 56. In a further modification the cam groove 72 is adjusted to increase the metered fuel charge available for acceleration below a predetermined speed and the shoulder 83 has a reduced diameter portion to spill off a very small part of the charge so that at the full throttle rated speed the fuel delivery is equal to that pumped by the metering piston in Fig. 6. In another embodiment a spill-off valve 141, Fig. 10 (not shown), controlled by air intake manifold pressure prevents over-fuelling of a turbosupercharged diesel engine under quick acceleration conditions. When throttle 56 is open more than three-quarter, pressurized fuel in conduit 27 passes via port 122, passage 121, port 123 and conduit 124 leading into chamber 125 to move valve plunger 120 against spring 127 to stop 126. A turbo-charger 131 supplies pressurized air to manifold 132 and through conduit 133 to chamber 134 where it acts on diaphragm 135 and valve 130 against spring 136 to close spill-off valve 141. When valves 128 and 141 are open the full fuel charge pumped by the metering piston 3 cannot reach the injectors until sufficient air pressure is present in chamber 134. In further modifications valve 120 may be omitted and conduit 27 is connected directly to chamber 125.