A study of hydraulic force components applied to spool plungers of autonomous single-stage electro-hydraulic steering actuators

The paper presents the results of a study of hydraulic force components acting on spool plungers in autonomous one-stage electro-hydraulic steering actuators with two- and four-throttle electro-hydraulic amplifiers with underlapping of throttle openings by spool plungers used in space rocket stages. The hydraulic force components acting on spool plungers in electro-hydraulic amplifiers of steering actuators that are examined in the paper are hydrostatic forces and stationary components of hydrodynamic forces (hydrodynamic forces during steady-state rates of flow around the spool plungers). The studies are conducted using the techniques of static analysis employing math models for optimized steering actuators. Computational experiments established that the cause of static instability in the steering actuator with four-throttle electro hydraulic amplifier with underlapping of throttle openings by spool plungers is the stationary component of the hydrodynamic force acting on the spool plungers of the electro-hydraulic amplifier, while the two-throttle steering actuator exhibits static stability. The study reveals that the steering actuator with four-throttle electro-hydraulic amplifier with underlapping of throttle openings by spool plungers is characterized by work process, while the steering actuator with two-throttle electro-hydraulic amplifier with underlaping of throttle openings by spool plungers does not exhibit such properties.