Combining Leakage and Orifice Flows in a Hydraulic Servovalve Model1

Abstract

Experiments indicate that at small servovalve spool displacements, leakage flow between the valve spool and body dominates the orifice flow through the valve. In precision positioning applications, where the servovalve operates within the null region, this flow, if ignored, may severely degrade the performance of a conventional servohydraulic design. We have developed an improved servovalve model that combines both leakage and orifice flow. The model was developed by reviewing experimental leakage flow data and identifying a simple mathematical form that (1) made physical sense and (2) replicated experimental data. When combined with orifice relations, the model extends the accuracy and region of applicability of existing servovalve models. Furthermore, the combined model is easily parameterized using available manufacturer data. [S0022-0434(00)00403-2]

A Method of Designing a Robust Force Controller of a Water-Hydraulic Servo System

“…The length Ks" Ro represents overlap length of the spool in its central position . Mathematical representation of flow characteristics has been investigated and a useful model was proposed by Eryilmaz [14]. Modifying the Eryilmaz's model for a single port configuration as shown in Fig .…”

A Bayesian approach for sealing failure analysis considering the non-competing relationship of multiple degradation processes

“…The high frequency and numerous sliding operations results in the wearing of spool and sleeve, making the sealing deteriorated, and eventually leading to the sealing failure. The leakage, usually caused by the wear degradation of spools and sleeves, is the main failure mode of this device, and has been investigated by many studies [2,4,5,19]. However, the detailed analysis of this wear degradation process has not been well studied.…”

Position Control of Electro-hydraulic Actuator System Using Fuzzy Logic Controller Optimized by Particle Swarm Optimization

“…X0 is equivalent to a spool displacement that would result in the same amount of flow in a nonleaking servo valve as the leakage flow rate in a leaking servo valve with a centered spool. Since the leakage resistance increases at larger valve openings, the leakage flow rate is inversely proportional to the spool displacement [15] . The relations for orifice and leakage flow at the servo valve ports form the basis of the servo valve flow model.…”

“…At small servo valve spool displacements, the leakage flow between the valve spool and body dominates the orifice flow through the valve [15] . In precision positioning applications, where the servo valve operates within the null region, this flow, if ignored, may severely degrade the performance of a conventional servo hydraulic design.…”

“…In this study, an accurate model of leakage flow [15] that takes into consideration the leakage flow and orifice flow is applied. By making smooth transition between them would likely improve the precision of the servo hydraulic system design and performance.…”