B010638 - ELECTRICAL,  HYDRAULIC AND PNEUMATIC DRIVE UNITS

Italian

Generation and distribution of compressed air. Air treatment units. Linear and rotational pneumatic actuators. Directional, regulation and safety valves.

Oleodynamic pumps and motors. Cilynders. Valves. Proportional oleohydraulics. Pressure and flow control components. Tanks, pipes, seals. Hydraulic systems design.

Electric servomechanisms. Motor-load coupling. Motion laws for cyclic duties. Thermal problem for electric actuators. Electric actuators. Electronic converters. Transducers

FESTO - Principi di Pneumatica
ASSOFLUID - Oleodinamica
Legnani-Tiboni - Meccanica degli Azionamenti (vol. 1 Azionamenti Elettrici)

The course aims at providing basic knowledge of electrical and fluid power components and their use in design of Mechanical Engineering and Automation.

Basics of physics, basics of mechanical and electrical engineering

Classroom lessons, laboratory activities and educational visits to factories.

Oral exam focusing on the topics of the course.
Questions regarding the fundamentals of fluid power components and electric actuators.
Then, the discussion of a practical problem concerning the design or analysis of a complex system of actuators.
The exam will assess the assimilation of the required levels of knowledge (in particular, cc3, cc5 and cc6) and skills (ca3, ca5 and ca6) proposed in the course.

Introduction to pneumatics. Characteristics of air. Classification of pneumatic devices. ISO Symbols
Physics of the air. Fundamentals of gas.
Gas Laws. Problems and examples. Outflow of gas. Problems and
examples.
The compressed air. Technical properties of compressed air.
Compression.
Compressed air and compressed air treatment.
Lubrication of compressed air. FRL.
Sizing of tanks.
Compressed air distribution: networks and flexible connections.
Examples.
Pneumatic actuators. classification. Pneumatic cylinders: description,
static and dynamic sizing.
Lateral load. Peak load. Air consumption.
Linear actuators. Rotary actuators. Special actuators.
Oil-air unit. Air Motors.
Pneumatic valves. Direction-controlling valves: types.
Pneumatic valves. Valve-controlling direction: name, drive, connection.
Sizing of pneumatic valves. Flow control valves. Pressure-reducing
valves.
Auto-switching valves. Special valves. Proportional technology.
Vacuum technique. Generating empty. Suckers.
Sensors and Transducers.
Introduction to hydraulics, hydraulic press, an example of simple circuit.
Working fluids, general characteristics, viscosity dependence on
temperature and pressure, viscometers, modulus of compressibility,
characteristics of flame retardant types of pumps: positive displacement
dynamics.
Hydraulic power generation, pumps construction types.
Pumps: foondamentali equations. Linear actuators: main types and the
basic equations.
Example of maximum size of cylinder-pump circuit.
Hydraulic motors, construction types, measures for the proper
functioning of the pistons in the engine piston fixed radial and axial
piston motors (differences between body and inclined plate).
Hydraulic motors, the basic equations, sample calculations on a hydraulic circuit.
Directional valves, seat valves, rotary and tray. Covering static and
transient in tray distributors. Distributors to control the pressure.
Operating range of spool valves, types of implementation of the
distributors, valves for controlling the pressure and flow, check valves.
Examples of hydraulic circuits to drive motors and cylinders.
Accessories (tanks, heat exchangers, filters).
Accumulators for hydraulic circuits, choice and design.

Introduction to electrical servomechanisms
Structure of an electric servo: converter, motor, controller, transducers, transmission, load.
Definitions. CEI Standards.
Electric servos, CNCs, PLCs. Multiaxial NC.
Motion control requirements: variation, control, following.
Specifications of the needs in a control problem.
Examples: machine tool, SCARA robot.
Motion control techniques: velocity, position, torque.
Open and closed loop control layouts.
Velocity controls.
Position controls. Position chase.
Torque controls.
Description of the main typologies of electric servomechanisms.
Motor-load coupling.
Introduction. Direct coupling or through a gearbox. Direct and retrograde motion.

Motor characteristic curves. Speed generator. Torque generator. Power generator.

Functioning as motor, brake or generator. Example (lift). Power flux associated.

Operating fields of a motor.
Characteristic curve of the load.
Locus of loads: definition. Locus of static loads. Locus of dynamic loads. RMS values of torque and angular speed.

Direct motor-load coupling, regime condition, transient.
Stability of regime condition.
Transient and start-up time.
Effect of the gear ratio. Introduction.
Power losses, direct and retrograde power flux. Reduction of torques and inertia. Regime. Transient. The flywheel.
Static and dynamic loads: classification.
Verification and choice of the motor size. Validation of the motor.
Choice of the motor and of the gearbox.
Choice of the motor and of the reduction ration for static load at constant speed. Example.
Choice of the motor and of the reduction ration for static load at variable speed. Adaptation of operational fields. Gearboxes.
Example of motor choice.
Choice of the motor and of the reduction ration for limited duration loads.
Choice of the motor and of the reduction ration for dynamic loads.
Motor-converter coupling. Machinery under periodic regime.
Loads with linear motion.
Elasticity in the mechanical transmission.
Simple motion laws for cyclic movements. Judgment parameters. Cycloidal motion law and with constant acceleration. Comparison.
5th degree polynomial law.
Minimum actuation time.
Improved motion laws. Seven stretches motion law with linear acceleration.
Minimum actuation time (in-depth analysis).

Thermal problem for electric actuators. Introduction.
Thermal balance of an electric motor.
Regime thermal behavior, nominal torque and power.
Thermal behavior during a transient with a constant load.
Thermal behavior: arbitrary and standard services.

Insulation classes, protection level, derating.

Overload of motor, converter and protections.