Development Of Electro-pneumatic Fast Switching Valve

Presented by, Sachin Goel Sudhanshu Nahata

Electro-Pneumatic Valves On-Off type Simple on-off functions

Servo Valves high linear control accuracy in

pneumatic actuators Costly, complex and bulky

Objective To develop electro-pneumatic valve with following characteristics: High linear control accuracy in pneumatic actuators Low-Cost Simple Compact

Working Principle Working principle is the “Fast

Switching” using ‘pulse-width modulation(PWM)’ technique Fast Switching is also achieved by designing the valve in efficient way which is to be explained

Design of Valve

Why Fast Switching? As the valve begins to open, the flow force

helps the magnetic force to keep the valve open. The travel distance of the disc is kept as small as possible in order to benefit from high magnetic attraction force.

Application

Electro-pneumatic position control system with four prototype valves.

Working When valves 1 and 3 are open, the

cylinder extends When valves 2 and 4 are open, the cylinder retracts When all valves are closed, the cylinder rests The electromagnet can be actuated using pulse width modulation (PWM) technique with control implemented via analog circuits, digital logic circuits or a

Switching Characteristics Optimum working gap: 0.6 mm of total

gap, 0.14 mm of holding gap and 0.46 mm of travel distance An applied current of 6 A or higher provides a sufficient magnetic force to overcome the spring force at the beginning of switching of the valve At the end of switching, about 1.75 A of applied current is just enough to hold the disc against to the spring force with 0.14 mm of holding gap Current reduced to holding level after the

Time Delay Time delay (opening) is governed by (Td):

Spring force, magnetic force and pressure force From experiments: -Total time – 4.65 ms -Delay time – 3.2 ms, Travel time – 1.45ms Time delay (closing) is governed by : Force balance btw spring force, fluid force and the magnetic holding force From experiments: - Total time – 3.05 ms

Thank You…