GB1252437A - - Google Patents

Abstract

1.252,437. Regulating I.C. engines; fuel injection nozzles. C.A.V. Ltd. Jan. 15, 1969 [Feb.7, 1968], No. 5991/68. Heading F1B. I.C. engine liquid fuel pumping apparatus comprises a fuel pump (not shown) for charging an accumulator 10, Fig. 1 connected by a first conduit to the narrower end of a cylinder 25 accommodating a stepped piston 26, a second conduit connecting the wider end of the cylinder with the accumulator through a first valve 22 so that when the first valve is open the piston is moved towards a control stop 40 and when a timing valve 32, 33 is open the piston is moved towards the wider end of the cylinder to discharge fuel therefrom through a third conduit 36 and the timing valve to a fuel injection nozzle. The fuel pump supplies an accumulator 10, Fig. 1 through conduit 12 and non-return valve 11, the accumulator pressure being applied to a spring-loaded piston 14 which acts through a spring 17 on a piston 16. The latter is also subjected to a fluid pressure as described later. As accumulator pressure increases piston 14 moves piston 16 until a port in piston 16 registers with conduit 16 so that no further fuel passes to the accumulator and pressure is maintained therein at the predetermined value. An engine-driven distributer member 20 controls the delivery of fuel to individual injection nozzles through ports 31 as follows:- As a groove 22 moves out of register with ports 23, 24 the passages 30, 32 and 39 register with ports 31, 33 and 38 so that fuel pressure from accumulator 10 acting on the narrower end of piston 26 displaces the latter towards its wider end and fuel therefrom is displaced through port 36, groove 37 and the passage in piston 35 to port 33. Fuel then flows through an inlet passage 32 to an outlet port 31, the flow continuing until the passage 29 registers with a groove 27 connected via a passage 27a and a restrictor 28 with a drain. Pressure in the wider end of the cylinder 26 and the line to the injection nozzle falls rapidly so the valve in the nozzle closes and restrictor 28 controls the residual pressure. Further rotation of tne distributer member 20 causes return of the piston 26 to the position shown. The stroke of piston 26 is controlled by a stop 40 positioned by a cam 41 the axial setting of which is controlled in part by a manually adjustable member 42 which acts through a governor spring 43 and in part by an engine driven speed governor 44. A speed-dependent pressure downstream of orifice 48 is applied to one end of the distributer member 20 and to piston 16 and a load-dependent pressure downstream of orifice 49 is applied to the other end of the distributer member. The outer ends of the passages 32 communicate with helically disposed grooves so that the injection timing varies with the axial movements of the distributer member. A piston 50 subjected to the pressure downstream of orifice 48 acts as a maximum fuel stop. The interspace between the wider portion of piston 26 and the adjacent cylinder end-wall is in communication with a drain and in a modification a groove (127), Fig. 2 (not shown) in the narrower portion of the piston is in constant communication with the interspace, the angular position of the piston being operated by a rack bar (128) operated similarly to stop 40. When the drain connection is covered by the piston a hydraulic lock is created in the interspace preventing further movement of the piston. In a further modification the flow through the drain connection is controlled by an electromagnetic valve controlled by a transducer responsive to the position of the piston 26 and by a signal from member 41. Alternatively the ports 23 and 24 are replaced by an electromagnetic valve or the distributer member is replaced by cam-operated or electromagnetic valves. Pressure from the wider end of the piston 26 is communicated to passages 66 and 70, Fig. 4 of an electromagnetically operated fuel injection nozzle so that pressure acting on piston 68 opposes the force exerted by the high fuel pressure in inlet 66. Valve element 63 is moved by a small increase in fuel pressure when an armature 72 is moved by a solenoid 73. Inlet 70 may be connected directly to the accumulator.