Liquid fuel pumping apparatus

Claim 1

A liquid fuel pumping apparatus for supplying fuel to internal combustion engines the apparatus being of the kind comprising an injection pump adapted to be driven in timed relationship with an associated engine, the injection pump including a rotary body in which is defined a bore, a fuel transfer passage communicating with said bore, reciprocable plunger in the bore, cam means surrounding said body and operable to effect inward movement to the plunger to displace fuel through said transfer passage as the body rotates, a feed pump for supplying fuel under pressure through said fuel transfer passage to the injection pump, valve means for varying the outlet pressure of the feed pump so that it varies in accordance with the speed of the associated engine, 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 setting of said cam means thereby to adjust the timing of delivery of fuel by the injection pump, said fluid pressure operable means comprising in combination, a cup shaped piston mounted within a first cylinder, first resilient means for urging said piston towards one end of said cylinder, said cup shaped piston defining a second cylinder having its closed end remote from said one end of said first cylinder, a second piston mounted in said second cylinder, second resilient means for urging said second piston away from the closed end of said second cylinder, means connecting said second piston to said cam means whereby movement of the piston will effect variation in the timing of injection of fuel, conduit means for connecting said one end of the first cylinder with the feed pump and control means for admitting fluid under pressure to the closed end of said second cylinder depending upon the setting of said throttle member, said control means acting to lower the pressure of fluid in the closed end of said second cylinder when the throttle member is set to reduce the amount of fuel supplied by the feed pump to the injection pump whereby the pistons will move relative to each other against the action of the second resilient means.