Pneumatic motor or air motor
Air motors produce continuous rotary power from a compressed air system. The air vane motor is a very robust drive that is almost impossible to overheat. Unlike electric drives, the load can be too great without damaging the motor, e.g. by overheating.
Functioning air motor
The characteristic curve torque to rotational speed can be explained by the design. When the machine is at a standstill, the compressed air presses against the vanes with maximal pressure. As the speed increases, the vanes are pulled along by the compressed air. As a result, the pressure force and thus the torque of the motor decrease.
The applications are versatile. Above all, examples are to be mentioned here, in which explosion protection is necessary, for example chemical industry, painting plants and mining. Due to their small dimensions, they are suitable as a drilling unit, PU foam systems, mixing motors for spray heads, etc.
Controlling pneumatic motors
Controling the sense of rotation: If only one direction of rotation is used, a directional valve with 3 connections is used as control element. A reversal of rotation can be realized as illustrated with a directional valve, which has 5 connections (also used for double-acting cylinders).
Controling number of rotation: Generally, pneumatic motors are exhaust air throttled. Hereby you get a high tightening torque. Supply air throttling has the advantage that the air consumption is lower. However, the tightening torque is almost half as much as for exhaust air throttling.
Controling torque: Torque control takes place via a pressure control. Basically, the pressure regulator is installed in the supply line of the motor.
Advantages of air motors (vane motors)
- Do not overheat due to overload (generally applies to all pneumatic actuators).
- Since overheating due to high load is not possible, a high IP rating is possible, i.e. the housing can be sealed so that use under water is possible.
- Maximum torque is already possible at start-up
- High speeds are easily possible
- Insensitive to dust and heat
- As with all pneumatic actuators, the following applies here: Suitable for use in potentially explosive atmospheres.
A big disadvantage is that air motors consume relatively expensive compressed air, so the cost of operating them might be probably greater than that of operating electric motors.