Pneumatic knowledge sharing - Pneumatic actuator

Basics part

Basic structure of cylinder

The so-called pneumatic actuator is a component that uses compressed air as power, and the drive mechanism forms linear, oscillating and rotating motions.



Cylinder classification


Single-acting cylinder:

The piston is only supplied by the pressure reducing valve, and the air pressure pushes the piston to generate a thrust converter, which returns by spring or its own weight.




Double acting cylinder:

There is gas pressure at both ends of the cylinder piston to realize forward or backward movement.



Cylinder cushion

However, the cylinder also has a problem. If the cushioning device is not used, when the piston moves to the end, especially the cylinder with long stroke and fast speed, the kinetic energy of the piston top cover will become very large.

Therefore, we made a buffer design.


1. Hydraulic buffer

The first is to install a hydraulic injector at the front end of the cylinder.



In the form of RBQ series hydraulic mechanism, B uses a unique orifice design and uses mineral oil as the medium to realize the transition from high speed and light load to low speed and heavy load.


:: There is no adjustment in the wide range from small energy to large energy intensity, which can achieve the best energy absorption.


2. Rubber buffer

The piston rod is additionally provided with a cushion




1) The buffering capacity is fixed and unchangeable, and the buffering capacity is small. Small cylinders are used to prevent operating noise.

2) It is necessary to pay attention to the phenomenon of deformation and peeling caused by the aging of the rubber.


3. Air cushion

When the piston moves, the buffer sleeve and the sealing ring work together to form an air chamber/buffer cavity to achieve buffering.



When the opening of the cushion valve is very small, the pressure in the chamber rises rapidly, and this pressure produces a reaction force on the piston, which decelerates the piston until it stops.



1) By adjusting the opening of the buffer valve, the buffer capacity can be adjusted. The smaller the opening degree, the buffering force acts.

2) Use the back pressure of the cylinder to achieve cushioning. The cylinder back pressure is small. The buffer capacity will also become smaller. When using, pay attention to the control method of load rate and cylinder speed.


Lubrication of cylinder

In addition, we have to talk about lubrication, the purpose of which is to reduce the damage of the cylinder movement to the cylinder itself and to extend the cylinder replacement.

Lubricate the oil:

Use a lubricator to mix lubricating oil into compressed air and deliver it to the cylinder.


Only use built-in grease, no need to use oil mist for lubrication; avoid food and medicine packaging from being contaminated by oil during the transportation process, and the impact on industrial chemical pigments, or the accuracy of testing instruments.



Once used to lubricate the oil, it needs to be used continuously.