design of hydraulic systems

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DIGITAL proportional pressure control valves

Electrohydraulic proportional controls modulate hydraulic parameters according to the electronic reference signals.

They are the ideal interface between hydraulic and electronic systems and are used in open or in closed-loop controls, see section  , to achieve the fast, smooth and accurate motions required by today’s modern machines and plants.

The electrohydraulic system is a section of the overall automation architecture unit where information, controls, alarms can be transmitted in a “transparent” way to the centralized electronic control unit and viceversa also via standard fieldbus.

Proportional electrohydraulics provides the following advantages in comparison with the electromechanical systems:

·         intrinsic overload protection;

·         automatic force adaption;

·         fast operating response, self lubrification of the system;

·         simple stepless variation in speed, energy storage capability, high power density, forces and torques, long service life and high   reliability.

The core of electrohydraulic controls is the proportional valve that regulates a pressure P or a flow Q according to the reference input signal (normally ±10 VDC) supplied by the machine CNC. Particularly the proportional valve must be operated by an electronic driver which regulates a proper electrical current supplied to the valve’s solenoid according to the reference signal.

The solenoid converts the electrical current into a mechanical force acting the spool against a return spring: rising of the current produces a corresponding increasing in the output force and consequent compression of the return spring, thus the movement of the spool.

The proportional valves can be single stage or piloted, with or without pressure/position transducer. Proportional valves with transducer provide better regulation accuracy. In pilot operated executions the proportional pilot valve regulates flow and pressure acting on the main operated stage.

Atos proportional valves are equipped with ZO and ZOR, efficient solenoids (30 W and 40 W) respectively designed for direct-acting valves of  ISO 4401 size 06 and 10 and they are assembled in different options as follows:

·         A: without integral transducer, open loop;

·         AEB, AES: as A plus integral electronic driver, basic or  full;

·         R: with integral pressure transducer;

·         REB, RES: as R plus integral electronic digital driver, basic or  full;

·         T, L: with integral LVDT single/double position transducer, closed loop, featuring high static and dynamic performances;

·         TEB, TES, LEB, LES: as T, L plus integral electronic driver, basic or  full;

In the new generation of digital proportionals, the electronic driver is integral to the valves and it is factory preset to ensure fine functionality plus valve-to-valve interchangeability and to simplify installation wiring and system set-up.

For detailed information on Electronic drivers contact our technical office.

DIGITAL PROPORTIONAL RILIEF VALVES pilot operated, open loop, subplate or modular mounting

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DIGITAL PROPORTIONAL RILIEF VALVES with integral pressure transducer digital, pilot operated, closed loop high performances, rugged design

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