Control Circuit Development PDF

Control Circuit Development Electro-Pneumatic Control Circuits Basic General Design Principles Pneumatic circuit A pneumatic circuit is an interconnected set of components that convert compressed gas (usually air) into mechanical work. In the normal sense of t...

Control Circuit Development Electro-Pneumatic Control Circuits Basic General Design Principles Pneumatic circuit A pneumatic circuit is an interconnected set of components that convert compressed gas (usually air) into mechanical work. In the normal sense of the term, the circuit must include a compressor or compressor- fed tank. Components of Pneumatic circuit Active components Compressor Transmission lines Air tank Pneumatic hoses Open atmosphere (for returning the spent gas to the compressor) Valves Passive components Pneumatic cylinders Structure of Pneumatic Control System System Circuit Diagram and Pneumatic Elements Control system development The development of the control system solution requires that the problem is defined clearly. There are many ways of representing the problem in a descriptive or graphical form. The methods of representing the control problem include : 1. Positional sketch 2. Displacement-step diagram 3. Control chart 4. Function diagram 5. Function chart 6. Circuit diagram Positional sketch Shows the relationship between the actuators and the machine fixture. The actuators are shown in the correct orientation. Not normally to scale and should not be too detailed. Displacement-step diagram The action (travel, stroke) of the piston rod of cylinder 1A from the retracted position (sequence state 1) to the extended position (sequence state 2) on the one hand, and from the extended (sequence state 2) to the retracted (sequence state 3) position on the other is represented graphically by function lines (action lines) as shown Displacement-time diagram Represent the displacement (travel) of power elements with a linear action over time. A variety of speeds can thus be described roughly in the diagram. Control chart The switching status of the control element is represented in relation to the steps or the time Function diagram A combination of the motion diagram and the control chart Displacement-step diagram with signal lines - If limit switch 2S1 is actuated and push button 1S 1 is pressed =>piston[1A] extends. - cylinder 1A reaches its forward end position=>li mit switch 1S3 is actuated =>piston[2A]advances. - cylinder 2A reaches its forward end position=> li mit switch 2S2 is actuated =>the piston rod of cyli nder 1A retracts. - cylinder 1A reaches its retracted end position=> the limit switch 1S2 is actuated => the piston rod of cylinder 2A retracts.cylinder 2A reaches its retr acted end position=>limit switch 2S1 is actuated => the initial position is reached again. Representation of signal lines Representation of input elements