The designs of Moog’s servovalves are based on a thorough knowledge of our customer’s motion control applications and their unique requirements, practical experience gained in the field and the use of innovative R&D technologies.
All of this know-how has been incorporated into the design of one of our newest products, the D672 Servovalve, a three stage size NG 16 servovalve featuring electrical feedback for the main stage and an NG06 pilot valve with a ServoJet® pilot stage. The digital valve electronics for closed-loop control of the pilot and the main stage are on the pilot valve.
The D672 Servovalve is ideally suited to demanding environments such as steel mills due to:
- Highly dynamic valve behavior
- Rugged, dirt-resistant valve design
- Ability to modify the flow characteristic curve to suit the customer's application
Rugged Valve Construction
Both the pilot valve and the main stage have a spheroidal-graphite cast iron valve body and a spool/bushing unit made from hardened steel without an o-ring. In such spool/bushing units without an o-ring, the pressure port "P" for the "A" and "B" ports is sealed simply by the joint between the bushing and the aperture in the valve body. Thus, only the outside of the bushing is sealed using o-rings which are subject to low hydraulic pressure resulting from fluctuating load conditions and pressure peaks.
The combination of a dirt-resistant ServoJet® pilot stage and a hardened spool/bushing unit without an o-ring for the pilot and main stages makes for a rugged valve with a long service life which complies with the latest ISO requirements.
Achieving Customer-Specific Performance
The sophisticated valve electronics allow for a linear characteristic flow curve as standard despite valve saturation and for the characteristic curve to be adapted to suit the customer's specific application.
New Port Pattern
The D672 Servovalve is the successor to our well-known D791 design, a main-stay of steel plants around the world. Please note that the D672 valve has a mounting pattern according to ISO 4401-07-07-0-02 and the D791 valve has mounting pattern according to ISO10372-06-05-0-92. When replacing a D791 in an existing application with the new D672 a mounting manifold block can easily be used to accommodate the two different mounting patterns.
Appendix: Technical Data Servovalve (D672)
Jürgen Hutzler is a Senior Product Engineer responsible for new product development for Moog’s Servo and Servo-Proportional Valves (D661, D662, D665) including development of the new NG16/25 Servovalve with Pilot D670. He has worked at Moog since 2000 and previously worked for 3 1/2 years for Vickers and Rexroth.