Fuel injection pumping apparatus

#This invention relates to liquid fuel injection pumping apparatus for supplying fuel to internal combustion engines, and of the kind comprising an injection pump driven in timed relationship with the associated engine, a feed pump for supplying fuel under pressure to the injection pump at a pressure which varies in accordance with the speed at which the apparatus is driven, a throttle member for controlling the quantity of fuel supplied to the injection pump and thereby controlling the quantity of fuel supplied to the associated engine, and fluid pressure operable means for controlling the timing of delivery of fuel by the injection pump.

#The object of the invention is to provide such an apparatus in a simple and convenient form.

#According to the invention, in a fuel injection pumping apparatus of the kind specified, said fluid pressure operable means comprises a fluid pressure operable piston which is movable against the action of resilient means to advance the timing of injection of fuel to the engine, the piston being moved by fuel under pressure from the outlet of the feed pump, and a fluid pressure operable stop member which when the apparatus is at rest, positions the piston to provide the correct timing of injection of fuel for starting purposes.

#One example of a liquid fuel injection pumping apparatus in accordance with the invention will now be described with reference to the accompanying drawings, in which:

#FIG. 1 is a sectional side elevation showing one form of pumping apparatus to which the invention can be applied, and

#FIG. 2 shows in sectional plan view a portion of the apparatus not seen in FIG. 1.

#With reference to the drawings, there is provided a body part 1 which at one end contains a feed pump 2 of the kind comprising a rotary impeller provided with vanes. The inlet 3 and outlet 4 of this pump are interconnected through a relief valve 5 which regulates the pressure of fuel delivered to the rest of the apparatus in a manner dependent upon the speed at which the feed pump is driven. At the other end of the body part is contained a fuel injection pump which comprises a rotary head 6 formed at one end of a distributor 12 which serves to interconnect the rotary parts of the feed and injection pumps. Formed in the head is a transverse bore 7 containing a pair of reciprocable plungers 8 which through rollers 9 at their outer ends, co-operate with a surrounding annular cam 10. Furthermore, the distributor is adapted to be driven in synchronism with an engine with which the apparatus is associated, through a drive shaft 11.

#Fuel from the feed pump 2 is fed through a passage 13 in the body part to an annular groove 14 in the periphery of the distributor and thence by way of a throttle valve 15 to a passage 16 in the body part which registers in turn as the distributor rotates, with a plurality of radially disposed passages 17 formed in the distributor. The passages 17 are in communication with an axial passage 18 in the distributor which opens at one end into the bore 7 in the head. Also extending from the axial passage 18 is a radial passage 19 which is adapted to register in turn and as the distributor rotates with a plurality of outlet ports 20 formed in the body part and which are adapted for connection to the injection nozzles respectively of the cylinders of the associated engine.

#The apparatus so far described, is well known and operates in the following manner. Fuel from the feed pump is fed intermittently by way of the throttle valve to the axial passage 18 in the distributor and thus serves to move the plungers of the injection pump outwardly. At appropriate instants in the cycle, the plungers are moved inwardly by the action of the cam and thereby serve to discharge fuel in turn to the engine cylinders.