Introduction
Rotary vane pumps are a type of positive displacement pump. This type of pump is often used in hydraulic systems, for aeration (pumping air) and for vacuum systems. Unlike centrifugal pumps, vane pumps are self-priming.
There are several variations of vane pumps commonly available, these include the balanced, unbalanced, fixed and variable delivery type vane pumps.
Components
Rotary vane pumps are more complex than gear pumps, or piston pumps. The main body of the pump consists of a cam ring, rotor and vanes. A filter -or multiple filters- is used on the suction side to prevent foreign particle ingress and subsequent damage to the pump internals. An electric motor is used to rotate the pump.
Rotary Vane Pump Parts
How Rotary Vane Pumps Work
The below video is an extract from our Introduction to Electrical Transformers Online Video Course.
The flowing medium (gas, liquid or vapour) is drawn into the pump through the suction port. The medium enters the space between a pair of vanes. The volumetric space between the cam ring and rotor, gradually increases. As the rotor rotates, the medium becomes trapped between a pair of vanes until the discharge port is reached.
Vane Pump Suction and Discharge Port
The volumetric space between the cam ring and rotor gradually decreases as the vanes approach the discharge port. This reduction in space forces the medium to flow out of the discharge port.
At this point, the space between the vanes is empty and the process can be repeated.
Sealing of the space between the vanes and cam ring is achieved due to the centrifugal force applied as the rotor rotates, hydraulic pressure, or spring pressure (springs mounted behind the vanes).
The reason for the changing of volumetric space is due to the rotor being eccentric (offset) from the cam ring. If the rotor was placed directly in the centre of the cam ring, the pump would have no flow. The more eccentric the rotor is, the more flow can be achieved through the pump.
How to Vary Vane Pump Flow
Vane Pump Designs
Vane pumps are available in several common designs.
- Balanced - consists of one rotor, two cam rings, two suction ports and two discharge ports. The load upon the pump bearings is balanced due to the design.
- Unbalanced - consists of one rotor, one cam ring, one suction port and one discharge port. The load upon the pump bearings is not balanced. Unbalanced vane pumps are suitable for low load applications only.
- Fixed Delivery - a pump that delivers a fixed flow rate (assuming constant rotational speed).
- Variable Delivery - a pump that delivers a variable flow rate based upon the position of the cam ring to the rotor.
Advantages
Advantages associated with vane pumps include:
- Can pump gases, liquids and vapours.
- Self-priming.
- Very low pressure pulsations.
- Suitable for a wide range of pressures and temperatures.
- Quiet (not loud).
- Easy to maintain (especially if cartridges are used).
- Efficient (75-90%).
Disadvantages
Disadvantages associated with vane pumps include:
- Complex design.
- Sensitive to foreign particle ingress.
- Not suitable for abrasive systems.
3D Model Components
This 3D model shows all major components associated with a typical rotary vane pump, these include:
- Rotor
- Cam Ring (Stator)
- Vanes
- Motor
- End Plate
- Filters
- Muffler Box
Additional Resources
https://en.wikipedia.org/wiki/Rotary_vane_pump
https://www.quora.com/How-does-rotary-vane-vacuum-pumps-work