Rotary Vane Pump

Overview

A rotary vane pump moves liquid by trapping it in chambers that grow and shrink as a vaned rotor spins inside an offset ring. Because each turn displaces a fixed volume regardless of pressure, flow stays nearly constant and almost pulse-free, and the pump primes itself by pulling a vacuum at the inlet. Those traits make it a common choice for fuel transfer, light oils, solvents, refrigerants, and the vacuum stage of many machines.

The heart is the Cam Ring & Rotor, where the vanes sweep fluid around the Cam Ring. The End Plates & Shaft closes the chamber ends and carries the shaft, the Ports & Relief Valve times the suction and discharge and caps the pressure, and the Drive Motor spins the whole thing through the Shaft Coupling. The Pump Housing forms the wetted casing and the O-Ring Set seals it.

How it works

The Slotted Rotor is mounted off-centre inside the Cam Ring, so the gap between rotor and ring is large on one side and nearly closed on the other. Radial Sliding Vane blades slide out of their slots and ride the ring bore, helped out by the Coil Spring behind each and by centrifugal force once spinning. Each pair of vanes seals a pocket; as the rotor turns, that pocket expands on the inlet side and draws fluid in, then contracts on the outlet side and pushes it out. Lapped End Plate faces seal the pocket ends and set the running clearance that keeps internal leakage, slip, low.

Because the pump will keep building pressure into a blocked line until something gives, the Relief Valve sits across the ports: its Relief Poppet lifts against a spring once discharge pressure exceeds the set point and dumps flow back to suction. The Drive Shaft runs on Ball Bearing supports with an Oil Seal keeping fluid off the drive end, and the Port Plate aligns its kidney-shaped openings with the expanding and contracting chambers so suction and discharge are correctly timed. Vane pumps are valued for handling thin, low- lubricity fluids that would slip past a gear pump, and the vanes self-compensate for wear as they slide further out over time.