GB799111A - Improvements in and relating to liquid fuel injection pumps for internal combustion engines - Google Patents

Abstract

799,111. Fuel injection pumps. BRYCE BERGER, Ltd. July 12, 1956 [July 22, 1955], No. 21303/55. Class 102(1). In a fuel injection pump fuel enters through inlet 5 and is delivered to a chamber 6 by a lift pump 4. A rotating distributing shaft 18, formed as part of or connected to the driven shaft 3 has two radial cylinders housing pistons 12. The pistons have their outer ends in contact with rocking levers pivoted on crosspiece 7 of the shaft 3, the other end of the lever being in contact with a fixed outwardly acting cam 16. The distributing shaft 18 has two diametrically opposed drillings 25, which in turn provide connections to the engine cylinders, and spill ports 26. The lower end of the shaft 18 containing the spill ports has an axially sliding control sleeve 27, having a tapered slot 28 and a non-return valve 29. A passage 42 connects the downstream side of the valve 29 with the space 41 formed by the sleeve 27 and a plate 33 having an orifice 34 into which is inserted a needle 35. The widest part of the tapered slot 28 is at the top of the sleeve and the sleeve is biased in an upward direction by spring 36. In operation fuel is drawn into the pumping space 23 through ports 17, which may be provided with non-return valves. At the commencement of the pumping stroke of the pistons 12, one of the drillings 25 is in line with an outlet passage 22 to the engine cylinders and one of the spill ports 26 is in hydraulic connection with slot 28. Side valve 29 is arranged to open at a lower pressure than the inlet valve to the engine cylinder fuel passes through spill port 26, slot 28, valve 29, passage 42 to space 41 and then through the orifice 34 until the spill port moves out of hydraulic engagement with the slot 28. The pressure in the bore 24 then increases for the remainder of the pumping stroke and fuel passes through drilling 25 and passage 22 to the engine cylinder until the drilling moves out of line with the passage 22. If the speed of the engine increases more fuel will be pumped to the bore 24 and the pressure drop across the orifice will increase and cause the sleeve 27 to move downwards against spring 36 bringing a wider part of slot 28 into engagement with the spill ports 26 thus reducing the arc over which drilling 25 is in line with passage 22 after the spill port 26 has been closed to the slot 28. In the embodiment shown the sleeve is prevented from rotating by a spindle 30 and the initial axial position of the sleeve 27 is controlled by a handle 32. The spindle 30 may be replaced by a spring biased piston having an orifice connected to the chamber 6 so that increase in pressure in the chamber 6 causes a pressure drop increase across the orifice to move the piston against the spring, movement of the piston causes rotation of sleeve 27 and thus variation in the timing of fuel injection to the engine cylinders. The rocking levers causing actuation of the pistons 12 may be pivoted in axis parallel to or at right angles to the shaft 3 and these levers may be rocked through separate adjustable cams.