In this PPT, you can collect data regarding Pneumatic Control System & its various type of Components
Size: 1.98 MB
Language: en
Added: Dec 30, 2015
Slides: 24 pages
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SHRI S’AD VIDYA MANDAL INSTITUTE OF TECHNOLOGY PREPARED BY :- Urvesh Prajapati (140453119029). Aakash Rana (140453119030). Keval Rana (140453119031). Pinakin Rana (140453119032). SEMESTER :- 5 th Sem. DEPARTMENT :- Mechanical Department GUIDED BY :- Dhaval P atel Topic:- Pneumatic control system and it’s components
Content 1. Basics of Pneumatics 2. Advantages & dis-advantages 3. Pneumatic Components Pneumatic Compressor Air Conditioners Air pressure regulator Air lubricator Air service unit Pneumatic Silencer 4 . Pneumatic Valves Pneumatic Actuators Directional control valve Shuttle valve
1. Basics of Pneumatics A pneumatic system is a system that uses compressed air to transmit and control energy. Pneumatic systems are used in controlling train doors, automatic production lines, mechanical clamps.
2. Advantages & Limitations of pneumatic systems The Advantages of pneumatic systems High effectiveness High durability and reliability Simple design High adaptability to harsh environment Safety Easy selection of speed and pressure The Limitations of pneumatic systems Relatively low accuracy Low loading Processing required before use Uneven moving speed Noise
3. Pneumatics Components A compressor is a machine that compresses air or another type of gas from a low inlet pressure (usually atmospheric) to a higher desired pressure level. This is accomplished by reducing the volume of the gas. Air compressors are generally positive displacement units and are either of the reciprocating piston type or the rotary screw or rotary vane types.
Piston compressor In this type of compressor a cylinder bore encloses a moving piston. As the crankshaft of the compressor rotate, the piston moves within the cylinder, similar to the piston in a car engine. As the piston is pulled down, the volume increases, creating a lower atmospheric pressure in the piston chamber.
Vane compressor The following figure shows a cutaway view of the sliding-vane-type rotary compressor . The air inlet is placed where the volume of the compression chamber is greatest , the outlet where the volume is smallest. Consequently, as the vanes turn, the space between them is reduced.
Screw compressor There is a current toward increased use of the rotary-type compressor due to technological advances, which have produced stronger materials and better manufacturing process . during the rotation of the rotor, air is drawn through the suction port to fill the space between the male and female rotor lobes.
Lobe compressor In this type of compressor the rotors do not touch and certain amount of slip exists. This slip increases as the output pressure increases. It is therefore operated at maximum speed for the highest efficiency. bar is obtainable with this type of constant displacement compressor .
Air Conditioners Air filters :- The air needs to be filtered to be free of moisture and contamination. Air filter is used to do this job. The filter elements remove the particles and moisture as small as 5 microns.
Air pressure regulator The pressure regulator is used to adjust the desired pressure for the pneumatic system. This use a piston to sense downstream pressure fluctuations. As the pressure downstream drops it is sensed by the diaphragm and the popper valve opens. This adjusts the position of the poppet valve, which limits the downstream pressure to the pre-set valve.
Air lubricator A lubricator ensures proper lubrication of internal moving parts pneumatics components . The proportional increase in oil mist by an increase of air flow is achieved by the spring loaded poppet assembly. As the flow increases and the valve opens , the area is increased and a pressure differential created .
Air service unit Filters, regulators and lubricators can be combined to ensure optimum compressed air preparation for a specific pneumatic system .
Pneumatic Silencer To decrease the noise of air in the outlet of valves, a silencer can be used. They are made from the porous plastic or bronze. Some of them are equipped with a control flow valve to control velocity of flow in the outlet of valves as well.
4. Pneumatic Valves The pneumatic valves are similar to hydraulic valves in terms of physical concepts. They are categorized into three classes:
Pneumatic Actuators Pneumatic Cylinders :- The cylinders converts the energy of the compressed air into linear motion which extend or retract the piston rod .
Pneumatic Rotary Actuators :- The rotary actuators converts the energy into a rotary motion. Most of them is Vane air motor.
Pneumatic Semi-Rotary Actuators :- Limited rotary motion can be achieved by incorporating a rack and pinion into a linear actuator or as seen opposite by a Vane Mechanism within the body of the cylinder.
Directional control valve Directional control valves ensure the flow of air between air ports by opening, closing and switching their internal connections. Their classification is determined by the number of ports, the number of switching positions, the normal position of the valve and its method of operation. Common types of directional control valves include 2/2, 3/2, 5/2, etc .
Shuttle valve Shuttle valves are also known as double control or single control non-return valves. A shuttle valve has two air inlets ‘P1’ and ‘P2’ and one air outlet ‘A’. When compressed air enters through ‘P1 ’, the sphere will seal and block the other inlet ‘P2’. Air can then flow from ‘P1’ to ‘A’. When the contrary happens, the sphere will block inlet ‘P1’, allowing air to flow from ‘P2’ to ‘A’ only .
Pressure control valve P ressure is controlled based on the outlet pressure. A feedback is given from the outlet to the control mechanism which is normally open type. The exit pressure acts on the controlling diaphragm. the outlet pressure is to be maintained constant. When the outlet pressure increase, the valve gets closed more and the flow of air is reduced. When there is a change in outlet pressure, this is communicated to the diaphragm. the diaphragm will move upwards or downwards depending on the outlet pressure. In case of the outlet pressure reduced, then the valve will get lifted up and the opening of valve will increase t he flow rate of air.
Flow control valve A flow control valve is formed by a non-return valve and a variable throttle.