Abstract:
A primary vane pump has a rotor with vanes, and an intermediate casing, which is also rotatable, both mounted in a fixed housing. The rotor vanes are enclosed in the casing and provide a primary pumping stage. The rotatable intermediate casing has outer vanes enclosed within the fixed housing, which provide a governor stage vane pump when the casing rotates. An inlet annulus supplies fuel to passages in the rotatable casing leading to the primary pumping stage and other passages in the rotatable casing conduct pumped fluid out to a discharge annulus. A closed fluid loop is established from discharge annulus to the governor stage vane pump, out through a valve and back to the discharge annulus. The reaction on the casing caused by the primary pump rotor tends to rotate the intermediate casing, while pressure drop through the valve in the closed fluid loop resists rotation. Adjustment of the valve adjusts rotational speed of the intermediate casing and varies the delivery rate of fuel by the primary vane pump.