Patent GB-1497505-A (GB)
Title: Fuel injection pump and injection control system therefor
IPC: F02D1/02
Filed: 1976-02-05
Abstract: 1497505 Fluid-pressure servomotor systems STANADYNE Inc 5 Feb 1976 [11 Feb 1975] 04533/76 Heading G3P In a fuel injection pump, a cam ring 19 controling the timing of injection is rotated by a piston 152 in response to movement of a valve 172 actuated through a beam 168 by cam surfaces 160, 164 on pistons 130, 122, the piston 130 being positioned in accordance with engine speed and the piston 122 in accordance with the quantity of fuel to be injected per stroke. Feedback from the piston 152 to the valve 172 is provided by a cam surface 186 and a sleeve 174 while a similar arrangement 124, 100 provides feedback to a valve 112 controlling the position of the piston 122, the valve being adjusted by a hand throttle 80 acting through a spring 92 and by an opposing fluid-pressure applied through a port 68. This pressure, corresponding to the square of the engine speed, is derived from a valve 36 actuated by fly weights 45 and is also applied to a valve 134 having a moving-seat, followup relationship with the piston 130. A pump 18 drawing fuel from a tank and delivering it to a charging port 33 of the pump distributer at a pressure regulated by a by-pass valve 20 also delivers fuel through passages 34 to the inlet of the valve 36 and to the inlets of the valves controlling the pistons 122, 130, 152. Supply of fuel to the distributer is interrupted by a valve 32 if a solenoid 63 is de-energized or the engine speed rises sufficiently for the fly weights to compress a spring 56 and displace a push-rod 60. A stop 222 normally clear of the lower abutment 94 for the spring 92 determines the maximum quantity of fuel which may be delivered per stroke and is adjusted both in accordance with engine speed by a cam 214 and by engine manifold pressure acting on a spring- loaded eccentric through a diaphragm 226. A second diaphragm 200 operates a pivoted stop 196 to engage the beam 168 and advance the injection timing if the manifold pressure falls below a predetermined value. During starting, the piston 122 is displaced by a spring 212 to maximum fuel position since no pressure is supplied by the transfer pump to a space 209 so that a piston 208 carrying a stop 206 is retracted by a spring 210. The piston 208 prevents fuel under pressure reaching a space 120 to the right of the piston 122 and also prevents operation of the piston 152 so that the maximum fuel charge is supplied with retarded timing. In a second embodiment, the piston (122a) Fig. 4 (not shown), regulating quantity of fuel is controlled by a sleeve valve (250) surrounding the valve (36a) operated by the fly weights 45. A further sleeve (252) surrounding the sleeve (250) is operated by a cam surface (126a) to provide feedback. A maximum fuel stop (222a) is operated by a cam surface (214a) on the speed-responsive piston (130a) and the further cam surfaces 160, 164 operate a valve (370) through a beam (168a) and a spring (360); the valve (370) serves to control a further valve (350) for adjusting the injection-timing piston (152a). A pivoted over-ride stop (388) may act on one end of the beam under control of a piston (380) to which pressure is applied by a servovalve (398) responsive to engine manifold and transfer pump output pressure. A further piston (414) controlled by the valve (398) operates a further stop (422) for the sleeve (250) to cut back the fuel supply. A valve (294) closed by a spring (296) in the absence of transfer pump output pressure ensures that the pistons (122a) and (152a) are moved to maximum fuel and maximum retardation positions, respectively, for starting. In the event of malfunction of the governor or feedback sleeves (250, 252) pressure is automatically applied to a piston (290) to close the valve 32.