Multi-actuator Switch-mode Hydraulic System a Major Qualifying Project Report
Current hydraulic systems involving multiple actuators and a single hydraulic power supply generally have poor efficiency. Using throttling valves to control multiple actuators requires meeting the highest pressure requirement and the total flow of all of actuators. When there is a large difference in the pressure requirement of the actuators, fluid throttling results in significant energy losses. The purpose of this project is to implement switch-mode control in a multi-actuator circuit and demonstrate the improvement in efficiency over a traditional hydraulic system with throttling valve control. To accomplish this task a hydraulic crane arm powered by two actuators was designed and constructed. One actuator provides a pivoting motion utilizing low pressure and high flow, while the other provides a lifting motion utilizing high pressure and low flow. Using a simple feedback control loop, the crane arm lifts, rotates, and lower a load. After designing and testing the hydraulic crane, the team concluded that high-speed switch technology with multiple actuators is feasible. This new technology, once implemented on a larger scale in realistic applications, will reduce losses in hydraulic systems that depend on multiple actuators to function.
Fluid Power Circuits and Controls
Preface BRIEF OVERVIEW OF FLUID POWER Introduction Concept of Fluid Power Summary FLUID POWER BASICS Introduction Fluid Statics Functions of a Working Fluid Fluid Properties Flow in Lines Leakage Flow Orifice Equation Summary Data Selected for Hydraulic Fluids PRESSURE CONTROL Introduction Review of Needed Symbols Relief Valve Unloading Valve Sequence Valve and Pressure-Reducing Valve Counterbalance Valve and Brake Valve Summary CREATION AND CONTROL OF FLUID FLOW Introduction Fixed Displacement Pumps Fixed Displacement Pump Circuits Variable Displacement Pump Circuits Comparison of Pump Performance Characteristics for Three Main Designs Multiple Pump Circuits Pump Mounts Flow Control Valves Circuits Using Flow Control Valves Summary ROTARY ACTUATORS Introduction Stall Torque Efficiency Typical Performance Data for a Gear motor Comparison of Motor Performance Characteristics for Three Main Designs Performance Characteristics of Low-Speed, High-Torque Motors Design Example for Gear Motor Application Interaction of Pump and Motor Characteristics Bent Axis motors Radial Piston motors Motor-Gearbox Combinations Oscillating Actuator Summary Curve Fitting Technique HYDROSTATIC TRANSMISSIONS Introduction Mechanical Transmissions Introduction to Hydrostatic Transmissions Hydrostatic Transmissions for Vehicle Propulsion Different Configurations of Hydrostatic Transmissions to Propel Vehicles Classification of Hydrostatic Transmissions Closed-Circuit Hydrostatic Transmissions Closed-Circuit, Closed-Loop Hydrostatic Transmissions Hydrostatic Transmission Design Summary Basic Concepts in Traction Selected Catalog Data for Hydrostatic Transmission Design Problems LINEAR ACTUATORS Introduction Analysis of Cylinders in Parallel and Series Synchronization of Cylinders Cushioning Rephasing of Cylinders Presses Load Analysis Types of Cylinders Cylinder Construction Summary TEMPERATURE AND CONTAMINATION CONTROL Introduction Temperature Control Contamination Control Summary AUXILIARY COMPONENTS Introduction Reservoir Hydraulic Lines Fluid Velocity in Conductors Options for Connecting Components Installation of Lines Design Life of Components System Integration Summary Selected Design Data for Fluid Conductors PNEUMATICS Introduction Orifice Equation Compressors Receiver Pipelines Preparation of Compressed Air Cylinders Motors Additional Actuator Units Valves Summary Standard Conditions SERVO VALVES Introduction Concept Servo Valve Construction Valve Performance Types of Servo Systems Servo Amplifiers Servo Analysis Summary PROPORTIONAL VALVES Introduction Types of Proportional Valves Analysis of Proportional Directional Control Valve Comparison of Servo and Proportional Valves Summary Summary of Equations Index
Correlations for mass transfer between fluidized spheres and a liquid
Abstract Data on mass transfer between the solid particles and the liquid in a fluidized bed have been analyzed. After a convenient selection, various correlations have been derived. They show that for a given fluidized system, the Sherwood number is independent on the Reynolds number.