Fuel injection pump with improved fuel metering - uses same solenoid valve for varying time-point of fuel release

摘要

The injection pump has a piston device (10,13) in a hole (11,12) and a bleed-off (20) from one end of the hole. The bleed-off is connected to an outlet of the nozzle (21). A fuel inlet is located at that end of the hole connected to a source of pressurised fuel. A valve prevents fuel flowing through this inlet whilst fuel is being delivered through the outlet. A plunger piston (24) moves backwards and forwards in a cylinder (33). A cam (25) moves the plunger piston to one end of the cylinder. A coupling hole (34) connects the end of the cylinder to the other end of the hole (11) so that pumped fluid acts on the piston when the plunger piston is moved by the cam. Consequently, the piston (10) that conveys the fuel through the bleed-off is moved. A solenoid-controlled valve permits fluid flow from the other end of the bore. A measuring valve transducer generates a signal indicating the piston's position. A control circuit is initiated by this signal to control the valve's operation. This circuit also receives demand and engine speed signals.