Fuel injection pumping apparatus

Claim 1

A fuel injection pumping apparatus comprising a high pressure pump arranged to deliver fuel at high pressure to an associated engine in timed relationship therewith, a low pressure pump for supplying fuel to the high pressure pump, first valve means for controlling the output pressure of the low pressure pump so that it varies in accordance with the speed at which the apparatus is driven, a fuel pressure operable resiliently loaded piston for adjusting a component of the high pressure pump so that the timing of fuel delivery by the high pressure pump can be varied, second valve means interposed between the low pressure pump and a cylinder containing the piston, a restricted flow path from downstream of said second valve means, said second valve means including a solenoid through which electric current can be passed to effect a control over the pressure applied to the piston, a spring loaded valve member which acts to effect a control over said pressure in the event of a cessation of current flow to the solenoid, said valve member defining a surface against which fuel under pressure from the outlet of the low pressure pump can act to oppose the action of said spring, movement of said valve member against the action of said spring allowing an increased flow of fuel through the second valve means, and an armature associated with said solenoid, said armature being connected to said valve member, whereby when said solenoid is energized, a force will be applied to the valve member in opposition to the force exerted by the spring.