This book provides a clear and concise overview of the basic principles of pneumatics technology, the design of pneumatic systems and the applications of the same for a host of engineering solutions, including industrial control. Designed primarily as an undergraduate textbook for mechanical, production, automobile and mechatronics engineering disciplines, it covers the subject in sufficient detail to be of use to postgraduate students as well as those preparing for competitive examinations.
The book employs numerous examples to bring forth the basic principles underlying the use of pneumatic power; it also provides physical interpretations of mathematical analyses for understanding the solutions of complex problems with ease.
Salient features:
T Jagadeesha is an assistant professor in the Department of Mechanical and Production Engineering at the National Institute of Technology (NIT), Calicut, Kerala. He teaches solid mechanics, mechanics of machinery, dynamics of machinery, design of machine elements, fluid power control, computational methods, industrial automation and robotics and mechatronics.
Preface xvAcknowledgements xvii1. INTRODUCTION TO PNEUMATICS1.1 Pneumatics and Its Meaning 11.2 History of Pneumatics 21.3 Pneumatic Systems 21.4 Choice of working Mediums 21.5 Advantages of Pneumatics over Hydraulics 41.5.1 Differences between hydraulic and pneumatic systems 51.6 Characteristics of Pneumatic Systems 51.7 Applications of Pneumatics 61.8 Properties of Air 71.8.1 Composition 71.8.2 Free air and standard air 81.8.3 Atmospheric pressure, gauge pressure and absolute pressure 81.8.4 Variation of pressure with altitude 101.8.5 Pressure ranges 101.9 Gas Laws 111.9.1 Boyle’s law 111.9.2 Charles’ law 131.9.3 Gay-Lussac’s law 141.9.4 General gas equation 151.10 Basic Components of Pneumatic Systems 161.11 Comparison of Hydraulic and Pneumatic Systems 181.12 Comparison of Different Power Systems 191.12.1 Electrical power transmission 191.12.2 Mechanical power transmission 201.12.3 Hydraulic power transmission 201.12.4 Pneumatic power transmission 20Summary 22Exercises 232. PREPARATION OF COMPRESSED AIR2.1 Air Preparation 272.2 Classification of Air Compressors 28viii Contents2.2.1 Reciprocating compressors 282.2.2 Rotary compressors 342.2.3 Dynamic displacement compressors (turbo compressors) 372.3 Comparison of Different Compressors 372.4 Control of Compressors 382.5 Selection and Specification of Compressors 382.6 Importance of Secondary Treatment 392.7 Aftercooler 392.7.1 Functions of compressed air aftercoolers 402.7.2 Types of aftercoolers 402.8 Drying of Compressed Air 412.8.1 Types of air dryers 412.8.2 Theory of drying 452.9 Storage of Compressed Air 492.9.1 Air receivers 492.9.2 Sizing of air receivers 51Summary 55Exercises 563. CONDITIONING AND DISTRIBUTION OF COMPRESSED AIR3.1 Fluid Conditioners 613.1.1 Air filters 623.1.2 Air regulator 643.1.3 Air lubricator 663.1.4 Filter–regulator–lubricator (FRL) unit 673.2 Air Distribution System 693.3 Guidelines for Component Selection 823.4 Guidelines for Compressor Sizing 83Summary 87Exercises 884. PNEUMATICS ACTUATORS AND AIR MOTORS4.1 Pneumatic Actuators 924.2 Types of Pneumatic Actuators 934.2.1 Types of pneumatic cylinders (Linear actuators) 934.3 Standard Metric Cylinders 1084.3.1 Graphic symbols for cylinders 1094.4 CylinderMountings 1104.5 Cylinder Force, Velocity and Power 1114.6 Acceleration and Deceleration of Cylinder Loads 1124.7 Linear Motion Using Pneumatic Cylinders 1144.7.1 Vertical cylinder 114Contents ix4.7.2 Horizontal cylinder 1154.7.3 Inclined cylinder 1154.8 Rotary Actuators 1204.8.1 Vane type actuators 1204.8.2 Rack and pinion rotary actuator 1224.8.3 Helix spine rotary actuator 1234.9 Air Motors 1234.9.1 Vane motor 1254.9.2 Piston motor 1264.9.3 Diaphragm air motor 1274.9.4 Turbine motor 1284.9.5 Gear motor 128Summary 129Exercises 1305. PNEUMATIC CONTROL VALVES5.1 Valves 1345.2 Direction Control Valves 1355.2.1 Types of direction control valves 1355.2.2 Non-return valves 1585.2.3 Flow control valves 1635.2.4 Pressure control valves 1645.3 Valve Specification 1675.4 Valve Sizing 1675.4.1 Valve sizing of flow control valves 1675.4.2 Sizing of direction control valves 173Summary 177Exercises 1786. SINGLE ACTUATOR CIRCUITS6.1 Pneumatic Circuits and Pneumatic Circuit Diagrams 1816.2 Single Acting Cylinder Control 1826.2.1 Direct control of a single acting cylinder 1826.2.2 Indirect control of single acting cylinder 1836.2.3 Control of a single acting cylinder using an ”OR” valve 1856.2.4 Control of single acting cylinder using an ”AND” valve 1866.2.5 Control of a single acting cylinder using a ”NOT” valve 1866.3 Direct Control of a Double Acting Cylinder 1876.3.1 Indirect control of double acting cylinder using a memory valve 1896.4 Supply and Exhaust Air Throttling 1896.4.1 Supply air throttling 1906.4.2 Exhaust air throttling 1906.5 Methods of Checking the End Position of a Cylinder 191x Contents6.5.1 Use of limit switches 1916.6 Pressure Dependent Controls 1996.7 Time Dependent Controls 201Summary 210Exercises 2117. MULTI ACTUATOR CIRCUITS – PART I7.1 Single Actuator vs Multi Actuator Circuits 2187.2 Classic or IntuitiveMethod 2197.2.1 Coordinated and sequential motion control 2197.2.2 Demonstration of the classic method 2197.2.3 Elimination of signal conflict 2317.3 Cascade Method 2347.3.1 Demonstration of the cascade method 2347.4 Step Counter Method 245Summary 286Exercises 2868. MULTI ACTUATOR CIRCUITS – PART II8.1 Pneumatic Logic Control 2928.2 Signal Processing Logic Gates 2938.2.1 OR Gate 2948.2.2 AND Gate 2958.2.3 NOT (Inverter) Gate 2958.2.4 NAND Gate 2968.2.5 NOR Gate 2978.2.6 XOR Gate (Exclusive OR) 2988.2.7 XNOR (Exclusive NOR) Gate 2998.2.8 NAND and NOR Universality 2998.3 Boolean Algebra 3008.3.1 Boolean algebra equalities or Identities 3018.3.2 DeMorgan’s Theorem 3038.3.3 Sum of Products (SOP) 3098.3.4 Product of Sums (POS) 3118.3.5 Analysis Using SOP and POS and Truth Table 3128.4 General Analysis of Karnaugh–VeitchMaps 3158.4.1 Condition of Adjacency 3158.4.2 Logic Circuit Design with Karnaugh–Veitch Mapping Method 3218.5 Compound Circuit Design 3388.6 Combinational Circuit Design 341Summary 344Exercises 345 Contents xi9. ELECTRO-PNEUMATIC CONTROL9.1 Introduction 3519.2 Control Electrical Devices 3529.2.1 Push button switches 3529.2.2 Limit switches 3549.2.3 Pressure switches 3559.2.4 Solenoids 3569.2.5 Relays 3589.2.6 Time delay relays (Timers) 3599.2.7 Temperature switch 3609.2.8 Reed proximity switches 3609.2.9 Electronic sensors 3629.2.10 Electric counters 3679.3 Electro-pneumatics Circuits for Single Actuators 3689.3.1 Direct control of single acting cylinder 3689.3.2 Indirect control of a single acting cylinder 3699.3.3 Direct control of a double acting cylinder 3699.3.4 Indirect control of a double acting cylinder (5/2 valve, singlesolenoid) 3709.3.5 Indirect control of a double acting cylinder (5/2 valve, doublesolenoid) 3719.3.6 Control of a double acting cylinder, OR logic (Parallel circuit) 3729.3.7 Control of a double acting cylinder, AND logic 3739.3.8 Latching circuits 3739.3.9 Double acting cylinder with automatic return (Spring return) 3769.3.10 Direct control of a double acting cylinder with automatic return(double solenoid) 3779.3.11 Indirect control of a double acting cylinder with automatic return(double solenoid) 3779.3.12 Automatic return of a double acting cylinder(using proximity switch) 3789.3.13 Oscillating motion of a double acting cylinder (Forward) 3789.3.14 Oscillating motion of a double acting cylinder (Return) 3799.3.15 Control systems with timed response 3799.3.16 Control of a double acting cylinder using an electric counterwith two end sensors 3819.3.17 Oscillation of a double acting cylinder using proximity switches 3839.3.18 Control of a double acting cylinder using a pressure switch 3839.3.19 Control of a double acting cylinder using a delay on and offtimer and counter 3849.3.20 Control of a double acting cylinder using a reed switch forinitial sensing 3859.4 Electro-pneumatic Circuits for Multi Actuators 3919.4.1 Two-group electro-pneumatic circuits 391xii Contents9.4.2 Design of three group electro-pneumatic circuits 400Summary 404Exercises 40510. PNEUMATIC CIRCUIT DESIGN USING PLCs10.1 Introduction 42310.2 Features of Programmable Logic Controllers 42410.3 Hardwired Control System 42410.4 PLC Systems 42510.5 Major Components of PLC 42610.6 Programming of PLC 42710.7 PLC Timers 43110.8 PLC Counters 43210.9 PLC Memory Elements 43310.10 Logic Design and PLC Circuits 44910.11 Areas of Application of a PLC 44910.12 PLC Standards 450Summary 451Exercises 45111. INTRODUCTION TO FLUIDICS11.1 Fluidics Defined 45511.2 Historical Background 45611.3 Advantages and Disadvantages of Fluidics 45611.4 Coanda or Wall Attachment Effect 45711.5 Basic Fluidic Devices 45811.6 Schmitt Trigger 46411.7 Turbulence Amplifier 46411.8 Fluid Sensors 46511.8.1 Types of fluid sensors 46511.9 Application Examples 46811.9.1 Control of a double acting cylinder 46811.9.2 Control of two double acting cylinders in sequence 46911.9.3 Continuous automatic reciprocation of a hydraulic cylinder 470Summary 471Exercises 47212. HYDROPNEUMATICS12.1 Introduction 47412.2 Hydropneumatic Circuits 47512.2.1 Air-oil reservoir 47512.2.2 Hydraulic check units 47712.2.3 Air-oil intensifier 478Contents xiii12.3 Comparison of Hydropneumatic, Hydraulic and Pneumatic Circuits 482Summary 483Exercises 48413. MAINTENANCE AND TROUBLESHOOTING OFPNEUMATIC SYSTEMS13.1 Maintenance of Pneumatic Systems 48513.2 General Maintenance Procedure 48713.3 General Maintenance Guide 48713.4 General Troubleshooting Guide 49313.5 General Troubleshooting Procedure 493Summary 508Exercises 509Index 511