PNEUMATIC
Pneumatics is an industrial science that includes training and applications aimed at converting gas pressure into mechanical movement. Practically, systems that work with vacuum and positive air pressure and the circuit elements used are considered within the scope of pneumatics.
As a different definition, "systems that use the energy stored as compressed air to do a useful job are called pneumatic systems." The air required for pneumatic devices is provided by a pressurized compressor. The compressor compresses the air and stores it in a sturdy, steel tank.
History
Pneumatics, which comes from the ancient Greek word "pneuma" meaning wind or breath (this word also means "spirit"), is the branch of science and engineering that studies the movement and control of mechanical systems working with compressed air. Today, it has also developed as a trade.
Compressed air was one of the first types of energy that humans used. Conscious perception of the weather, as well as conscious work with this tool, goes back centuries. The oldest known application is the air blower used around 2500 BC. The systematic use of pneumatics in power applications dates back to the mid-19th century. At that time, hand tools, drills, locomotives and similar power systems, especially those powered by compressed air, pioneered the development and rapid spread of pneumatics. However, modern control elements, which are still used in various applications today, first started to be used in the mid-20th century. In addition, air hunting guns and carbon dioxide cartridge guns used for hobby and sports purposes are also examples of pneumatic.
Gases Used in PNEUMATIC Systems
In most fixed and mobile applications, compressed ambient air is used. The two biggest reasons for this are the continuity of resource supply and the absence of any harmful waste.
Some small, self-contained systems may operate with gases that can cause respiratory problems. The most commonly used gases are nitrogen and carbon dioxide. Although it does not cause breathing problems in a pure oxygen environment, it is not used in pneumatic applications because it is very flammable.
Comarison with Hydraulic Systems
PNEUMATIC motion and control systems have some advantages over hydraulic and electrical systems. They operate at lower pressures than hydraulics, so pneumatic equipment is cheaper. They can achieve high operating speeds.
PNEUMATIC means a moving machine that works with gas pressure. With the emergence of the first steam boilers, the science of pneumatics emerged long before electricity and hydraulics (machines working with a fluid system).
The aim of PNEUMATIC is to perform the movement we want using air, CO2 or some kind of gas.
Machines operate at lower pressures than hydraulics. While values such as 1000 bar can be reached in hydraulics, standard working pressures in pneumatics are between 3 bars and 12 bars.
The biggest reason why PNEUMATIC systems are preferred is that they can reach very high speeds compared to other hydraulic and electric movement systems. Thus, they compensate for their low efficiency (25%-40%) with their speed.
PNEUMATIC systems are very easy to learn and use. Of course, this convenience also brings with it some costs. Since the production and maintenance of pneumatic systems are more costly, the industry is gradually moving away from pneumatics and towards electrical systems.
Compressors
It is the mechanical element that puts the air (gas) at higher pressure than the external pressure. There are 3 main types: Piston, Rotary cell (pallet) and Diaphragm. It is the flow generator of pneumatic systems. In this respect, they are similar to batteries and batteries. The air entering the compressor is humid, has the same pressure, and is of course the same pollution as the outside environment. It is pressurized in the compressor. At the exit, it is made clean, homogeneous and moisture-free with air conditioners.
Pistons are the movement mechanisms of pneumatic systems. As the gas fills the chamber inside the piston, the piston closes or opens. Thus, linear movement in both directions can be achieved.
The most commonly used piston types are the single-inlet spring-return piston and the 2-hole piston, one of which is at the beginning and the other at the end of the air intake hole.
When we give air to the single-inlet spring return piston, the piston moves out. When we cut off the air flow and allow the air inside to evacuate, the spring pulls the piston back.
In the other 2-hole piston type, when we give pressurized gas to one hole, the piston moves forward and when we give pressurized gas to the other hole, the piston moves to the other side. In this way, we have a two-way driven control piston.
cylinder piston
2-hole pistons are often used in industrial robot arms. Spring pistons, on the other hand, are mostly used in less sensitive works such as stamping, throwing and placing.
The ends of piston rods are usually externally threaded to accommodate additional parts.
Valves
Valves are the key to allowing pneumatic gas to pass or not. We can compare valves to relays or transistors in electronics. There are countless types of valves. Electric valves (electrovalves) are especially used in mobile robots and automation systems.
Electrovalve
Electrovalves are the most commonly used valve type in industrial systems. The controls are controlled electrically. We can think of it as a relay valve that allows the internal mechanism to change position.
When there is no electricity, gas enters the valve through one hole and exits through the other hole, depending on its normal state. The valve is providing flow.
When we apply electricity, the coil inside the valve becomes magnetized, closing the valve contacts or causing them to change position. Thus, the gas flow is cut off and the gases in the piston or system can be evacuated by opening the outlet hole and exhaust (discharge) hole.
Of course, what I have explained is only valid for the 3-way, 2-position electric spring valve.
You can find out how other types of electric valves work from their user manuals.
The first photo above is the one-way solenoid solenoid valve. The photo on the left is a two-way solenoid valve.
Valve Islands Valve Groups (Adavalves)
In mixed projects, instead of using all valves separately, group valves are made by using some common connections together (at least the main bodies). Thus, space is saved.
Ideal for more integrated systems.
Carbon dioxide tank Gas tanks
Such tanks maintain compressed gas at very high pressures. We can give deodorant bottles or diving tanks as examples of gas tanks. It is a mini tank that stores 12 grams of CO2 gas seen in the left photo. It is used in air guns. And of course, when we use a pneumatic system in a mobile robot, we use such small air tanks.
As we enlarge the tank (tube) we use, the power also increases. Larger tube, more gas flow rate.
For this reason, gas tanks that can be used in combat robots are limited to certain pressure and size criteria.
Multiplexer
The purpose of multiplexers is to transmit the incoming input to a certain number of outputs. The multiplexer in the example picture turns 1 main input (the hole designated as 1 or p) into 8 outputs.
PNEUMATIC
Barmeter, Pneumatic pressure gauge, Pressuremeter Barmeter – Pneumatic Pressure Gauges
The barmeter has 2 ports. When connected serially to the system, it shows the pressure information of the gas passing over it on its display.
Of course, this is not a very precise value because there are certain losses in gas pressure (0.3 - 0.4 bar) as the gas passes over such elements (indicator, valve, etc.).
It is used to check system health.
Regulators & Conditioners
Regulators fix the pressure of the gas coming to their inlets at the desired level. For example, if we want to obtain an outlet pressure of 6 bar, we give 8-9 bar to the inlet. We adjust the 6 bars from the upper adjustment screw.
Conditioners are integrated elements that include air dryer, regulator and gas lubricator.
counters
Counters are mechanical elements that show the number of gas pulses coming to their inputs and give output when it reaches a certain value.
It can be used to stop a piston after producing a certain number of strokes. They are frequently used in industry because they automate the system.
We can set the count value we want from the buttons on the counter valve.
Fittings
Mini fitting Connection Elements Fittings are basic connection elements. It can be used to connect 2 different diameter and sized pipes together or to get 2 separate pipe outlets from one pipe. There are many fittings used for different pressure values. Fittings do not leak gas up to maximum pressure values. When there is a malfunction in a system, I recommend that you first check whether the pipes are seated correctly in the fittings or not.
Other Pneumatic Elements
In this article, I mentioned a few basic elements that are most commonly used in pneumatics. Apart from these, there are countless other pneumatic elements. General gas pipes, silencers. There are also many special elements such as blind stoppers, cylinders without piston rods, valves with tilting spool sleeves, and throttle valves.