Fuel injection pumping apparatus with drain passage

Claim 1

A fuel injection pumping apparatus for supplying fuel to an internal combustion engine and comprising a body part having outlets, a rotary distributor in the body part, an injection pump, a delivery passage in communication with said injection pump and extending to the periphery of the distributor to register in turn with outlets in the body part during the time the injection pump supplies fuel to said delivery passage, said outlets in use communicating with injection nozzles respectively, a spring loaded delivery valve in said delivery passage, said delivery valve being opened by the flow of fuel from the injection pump and when the flow of fuel ceases said valve allowing a predetermined volume of fuel to return to said injection pump before it closes, and throttle means through which fuel can flow to said injection pump, a drain passage extending to the periphery of the distributor, said drain passage communicating with said delivery passage downstream of said delivery valve, a drain port formed in the body part for registration with said drain passage once per revolution of the distributor and during flow of fuel to said injection pump, and valve means in the body part for controlling flow through said drain port, said valve means including a valve member slidable within a bore, resilient means biasing the valve member to a first position, conduit means through which the valve member can be subjected to a fluid pressure which varies in accordance with the speed at which the associated engine is driven, said fluid pressure acting to move the valve member against the action of the resilient means to a second position which is attained when the speed of the associated engine has risen to above a predetermined value and passage means in said valve member and which in the second position of said valve member places said drain port in communication with a drain.