GB1029189A - Improvements in or relating to fuel injection pumps - Google Patents

Abstract

1,029,189. Fluid-pressure servomotor systems. M.J. BERLYN. Nov 5,1963 [Jan 23, 1963],No.43699/63. Heading G3P. [Also in Divisions F1 and F2] A fuel injection pump comprises a piston 26 reciprocable and rotatable in the bore 27 of a cylinder block 28 by means of a cam 16 and gearing 15,21, driven by a shaft 11. The cam 16 acts on a follower 40 the motion of which is transmitted to the piston 26 through a rocker 39,47 which oscillates about a shaft 49 one end of which carries a piston 50, Fig. 3, and the other a spring loaded crosshead 51. The piston 50 is housed in a cylinder 52 subject to the pressure of fuel entering through a duct 80. The piston 50, shaft 49 and crosshead 51 constitute an injection timing servomotor 57. The piston 26 is provided with a distributor annulus 62,a distributor slot 63 and a spill annulus 61 which communicates with an axial spill duct 59 via radial ducts 60. The bore 27 is provided with annular recesses 74,75,76,discharge,supply and spill recesses respectively. The head of the bore 27 has counter bores 66 and 67 which house a valve 69 mounted on a piston 65. The lift of the valve 69 from the seat 68 may be adjusted by varying the thickness of a shim 72. Fuel from the discharge recess 74 passes through a delivery valve 86, Fig. 2, to the distributor annulus 62 and the distributor slot 63 which serves a plurality of discharge ducts 73,Fig.1,in succession. The recesses 75,76, and counterbores 66 and 67 are connected by ducts, Fig. 8,to the injection timing servomotor 57, a duct 84 leading back to the fuel supply and a fuel transfer pump 25, constituted by by the gearing 15,21, contained in a casing 24, Figs. 1 and 8. The injection timing servomotor 57 is responsive both to the quantity of fuel injected and the speed of the pump 25. The quantity of fuel injected will govern the timing of the operation of the valve 69. The smaller the quantity of fuel injected the later the valve operation and vice versa. The valve 69 permits communication between ducts 124 and 121 tending to lower the pressure in the duct 80 to retard injection. Increase in speed of the pump 25 increases the pressure of the fuel supply which is transmitted to the duct 80 through ducts 82 and 81 to advance the injection. For increased speed of rotation of the pump 25,for a given quantity of fuel injected, increased pressure in duct 82 results and thus the injection timing is automatically advanced. Adjustable constrictions 126 and 127 are provided in the ducts leading from duct 80 to recess 67 and pump 25.