Fluid Power with Applications

Transcription

1 Fluid Power with Applications Sixth Edition Anthony Esposito Professor Emeritus Department of Manufacturing Engineering Miami University Oxford, Ohio Prentice Hall Upper Saddle River, New Jersey Columbus, Ohio

2 i Contents INTRODUCTION TO FLUID POWER Learning Objectives What Is Fluid Power? History of Fluid Power Advantages of Fluid Power Applications of Fluid Power Components of a Fluid Power System The Fluid Power Industry 17 Exercises 18 PHYSICAL PROPERTIES OF HYDRAULIC FLUIDS 21 Learning Objectives Introduction Fluids: Liquids and Gases Specific Weight, Density, and Specific Gravity Force, Pressure, and Head The SI Metric System Bulk Modulus Viscosity Viscosity Index Illustrative Examples Using the SI Metric System Key Equations 52 Exercises 53 vii

3 viii 3 Contents ENERGY AND POWER IN HYDRAULIC 57 SYSTEMS Learning Objectives Introduction Review of Mechanics Multiplication of Force (Pascal's Law) Applications of Pascal's Law Conservation of Energy The Continuity Equation Hydraulic Power Bernoulli's Equation Torricelli's Theorem The Siphon Energy, Power, and Flow Rate in the SI Metric System Illustrative Examples Using the SI Metric System Key Equations 99 Exercises 102 ft FRICTIONAL LOSSES IN HYDRAULIC PIPELINES 111 Learning Objectives Introduction Laminar and Turbulent Flow Reynolds Number Darcy's Equation Frictional Losses in Laminar Flow Frictional Losses in Turbulent Flow Losses in Valves and Fittings Equivalent-Length Technique Hydraulic Circuit Analysis Circuit Analysis Using the SI Metric System Key Equations 134 Exercises 135 E HYDRAULIC PUMPS 141 Learning Objectives Introduction 142

4 Contents IX Pumping Theory 144 Pump Classification 145 Gear Pumps 148 Vane Pumps 156 Piston Pumps 162 Pump Performance 171 Pump Noise 178 Pump Selection 184 Pump Performance Ratings in Metric Units Key Equations 188 Exercises HYDRAULIC CYLINDERS AND CUSHIONING DEVICES 195 Learning Objectives Introduction Hydraulic Cylinder Operating Features Cylinder Mountings and Mechanical Linkages Cylinder Force, Velocity, and Power Cylinder Loads Due to Moving of Weights Special Cylinder Designs Cylinder Loadings Through Mechanical Linkages Hydraulic Cylinder Cushions Hydraulic Shock Absorbers Key Equations 220 Exercises 222 HYDRAULIC MOTORS 227 Learning Objectives Introduction Limited Rotation Hydraulic Motors Gear Motors Vane Motors Piston Motors Hydraulic Motor Theoretical Torque, Power, and Flow-Rate Hydraulic Motor Performance Hydrostatic Transmissions 248

5 Contents 7.9 Hydraulic Motor Performance in Metric Units Key Equations 253 Exercises HYDRAULIC VALVES 260 Learning Objectives Introduction Directi6nal Control Valves Pressure Control Valves Flow Control Valves Servo Valves Proportional Control Valves Cartridge Valves Hydraulic Fuses Key Equations 304 Exercises 304 HYDRAULIC CIRCUIT DESIGN AND ANALYSIS 308 Learning Objectives Introduction Control of a Single-Acting Hydraulic Cylinder Control of a Double-Acting Hydraulic Cylinder Regenerative Cylinder Circuit Pump-Unloading Circuit Double-Pump Hydraulic System Counterbalance Valve Application Hydraulic Cylinder Sequencing Circuits Automatic Cylinder Reciprocating System Locked Cylinder Using Pilot Check Valves Cylinder Synchronizing Circuits Fail-Safe Circuits Speed Control of a Hydraulic Cylinder Speed Control of a Hydraulic Motor Hydraulic Motor Braking System Hydrostatic Transmission System Air-Over-Oil Circuit Analysis of Hydraulic System with Frictional Losses Considered 335

6 Contents xi 9.19 Mechanical-Hydraulic Servo System Key Equations 340 Exercises 340 I A HYDRAULIC CONDUCTORS AND FITTINGS 349 Learning Objectives Introduction Conductor Sizing for Flow Rate Requirements Pressure Rating of Conductors Steel Pipes Steel Tubing Plastic Tubing Flexible Hoses Quick Disconnect Couplings Metric Steel Tubing Key Equations 374 Exercises 374 ANCILLARY HYDRAULIC DEVICES Learning Objectives Introduction Reservoirs Accumulators Pressure Intensifiers Sealing Devices Heat Exchangers Pressure Gages FlowMeters Key Equations 416 Exercises O MAINTENANCE OF HYDRAULIC SYSTEMS 420 Learning Objectives Introduction Oxidation and Corrosion of Hydraulic Fluids Fire-Resistant Fluids 424

7 xii Contents 12.4 Foam-Resistant Fluids Fluid Lubricating Ability Fluid Neutralization Number Petroleum-Base Versus Fire-Resistant Fluids Maintaining and Disposing of Fluids Filters and Strainers Beta Ratio of Filters Fluid Cleanliness Levels Wear of Moving Parts Due to Solid-Particle Contamination of the Fluid Problems Caused by Gases in Hydraulic Fluids Troubleshooting Hydraulic Systems Safety Considerations Environmental Issues Key Equations 447 Exercises 448 < Q PNEUMATICS: AIR PREPARATION I O AND COMPONENTS Learning Objectives Introduction Properties of Air The Perfect Gas Laws Compressors Fluid Conditioners Analysis of Moisture Removal from Air Air Flow Rate Control with Orifices Air Control Valves Pneumatic Actuators Key Equations 498 Exercises 499 PNEUMATICS: CIRCUITS AND APPLICATIONS 504 Learning Objectives Introduction Pneumatic Circuit Design Considerations Air Pressure Losses in Pipelines Economic Cost of Energy Losses in Pneumatic Systems 510

8 Contents xiii Basic Pneumatic Circuits Pneumatic Vacuum Systems Sizing of Gas-Loaded Accumulators Pneumatic Circuit Analysis Using Metric Units Key Equations 528 Exercises 528 BASIC ELECTRICAL CONTROLS FOR FLUID POWER CIRCUITS 535 Learning Objectives Introduction Electrical Components Control of a Cylinder Using a Single Limit Switch Reciprocation of a Cylinder Using Pressure or Limit Switches Dual-Cylinder Sequence Circuits Box-Sorting System Electrical Control of Regenerative Circuit Counting, Timing, and Reciprocation of Hydraulic Cylinder 549 Exercises 551 FLUID LOGIC CONTROL SYSTEMS 555 Learning Objectives Introduction Moving-Part Logic (MPL) Control Systems MPL Control of Fluid Power Circuits Introduction to Boolean Algebra Illustrative Examples Using Boolean Algebra Key Equations 576 Exercises 576 ADVANCED ELECTRICAL CONTROLS 580 FOR FLUID POWER SYSTEMS Learning Objectives Introduction Components of an Electrohydraulic Servo System Analysis of Electrohydraulic Servo Systems 588

9 xiv Contents 17.4 Programmable Logic Controllers (PLCs) Key Equations 606 Exercises 607 APPENDIXES A Sizes of. Steel Pipe (English Units) 611 B Sizes of Steel Pipe (Metric Units) 613 C Sizes of Steel Tubing (English Units) 615 D Sizes of Steel Tubing (Metric Units) 617 E Unit Conversion Factors 618 F Nomenclature 620 G Fluid Power Symbols 623 H Answers to Selected Odd-Numbered Exercises 626 I Derivation of Key Equations 631 J Computer Analysis of Fluid Power Systems 636 K Exercises for Computer Solutions 644 INDEX 647