New high flow servo valve from Star Hydraulics

17 June, 2015

The Star series 902HF is for use in 3-way or 4-way applications within a closed loop control system of position, pressure (force) or velocity. Typical applications include:

• HAGC rolling mill.

• Resonant testing of turbine blades.

• Friction welding.

• Seismic exploration.

• Tensile/compressive testing.

• Aircraft structural testing.

• High rate tests.

The design consists of a 4-way, 2-stage pilot nozzle-flapper spool servo valve (pilot) providing high fidelity control to a main stage spool with a large cross-sectional area. The pilot can be supplied with a variety of flow rates, build materials and band-widths offering high performance and stability whatever the application demands, other pilot stage designs are also available.

The main stage has manifold interface for clean access to all ports including the pilot stage and is supplied as standard (6 port) where the pilot supply (X) and pilot return (Y) can be set at higher or lower levels to that of the main stage. The design can also be configured to accept traditional side entry pipe fittings such as SAE O-ring or BSPP thread forms.

The main stage consists of a stainless steel body and end caps machined from solid stock that houses a hardened sleeve and spool. The sleeve is available in a number of port sizes to govern the rated flow of between 450 l/m and 900 l/m at 35 bar per land. The spool and end cap arrangement can also be changed to reduce the spool drive area and therefore significantly increasing valve performance. Spool mass and flow characteristics have been optimised for dynamic applications.

[subhead] Non-contact inductive position transducer

The main spool has a non-contact inductive position transducer of robust design that can accept up to 10 kHz carrier frequencies and conditioned externally. Units may also be supplied with integrated control electronics constructed with surface mount technology powered by either a dual or single rail power supply. Input signals can be ±10 V, ±10 mA or 4...20 mA and actual spool position may also be monitored by similar signal types. Spool position null can also be adjusted via an externally adjustable potentiometer located on the main housing.

Modules can also be fitted between pilot and main stages to provide fail-safe conditions that can be pressure or solenoid activated.

• Rugged design.

• Precision positioning control.

• Integrated control electronics.

• High resolution.

• Very low hysteresis and zero point drift.

• 450 to 900 l/m rated flows.

• Replaceable sleeve.

• 3 levels of step and cyclic performance.

• 4, 5 or 6 port options.

• Pilot connection options.

www.star-hydraulics.co.uk