Analysis of Unsteady Flow Characteristics in Spool Valves for Mobile Hydraulics Machine Control

2018 ◽  
Author(s):  
S.-J. Oo ◽  
G. Kim ◽  
J. Do ◽  
S. Lee
Keyword(s):  
Control Systems ◽  
Discharge Coefficient ◽  
Flow Characteristics ◽  
Control Valve ◽  
Hydraulic Control ◽  
Transient Pressure ◽  
Servo Valve ◽  
Spool Valves ◽  
Opening And Closing ◽  
Spool Valve

The main control valve is a key part of mobile hydraulic control systems. The main control valve consists of several types of spool valves. A notch is usually introduced to the end of the spool valve to reduce the influence of the flow force generated by the movement of fluid. In this study the flowrate from a spool valve combined with a servo-valve system is controlled based on an accurate prediction of transient pressure-flow relations by CFD. The transient analyses inside the spool valves with three typical types of notch are performed using a commercial CFD code of Fluent™. The flow characteristics such as flow pattern, discharge coefficient, and flow force, which depend on the notch shapes and their openings, are analyzed via vorticity distributions. Hysteresis of flow coefficients is observed for opening and closing motions of the spool valve, which should be compensated by the servo-valve in order to control the designed rate change of flowrate.

Spool Valve Hydraulic Measurement Flow Pattern Error Based on Variable Discharge Coefficient

2015 ◽  
Vol 667 ◽  
pp. 444-448
Author(s):  
Zhuo Lin
Keyword(s):  
Flow Pattern ◽  
Discharge Coefficient ◽  
Compensation Method ◽  
Measuring Process ◽  
Important Method ◽  
Flow Pattern Transition ◽  
Spool Valves ◽  
Spool Valve ◽  
Submerged Discharge

Spool valves are the main elements in electro-hydro servo valves. Hydraulic measurement is an important method for spool valve’s null cutting measuring process. Because of the flow pattern transition, the discharge coefficient is a variable. This phenomenon causes errors if we assume the discharge coefficient is a constant as we always do. In this paper, the variable discharge coefficient is considered to the submerged discharge equation, and the flow pattern error is defined. For improving the precision of overlap values measurements, a compensation method of flow pattern error is presented in this paper.

A New Approach of Direct Digital Control for Spool Valves

1999 ◽  
Author(s):  
J. Ruan ◽  
R. Burton
Keyword(s):  
Digital Control ◽  
Stepper Motor ◽  
Hydraulic Control ◽  
New Approach ◽  
Control Approach ◽  
Speed Of Response ◽  
Spool Valves ◽  
Spool Valve ◽  
Direct Digital Control ◽  
Hydraulic Control System

Abstract In many applications, digital valves driven from stepping motors are often characterized by quantitative errors and in some cases, slow response. A new means of direct digital control is introduced for a spool valve actuated by a stepper motor. With this control strategy, both excellent speed of response and accuracy are simultaneously sustained for the valve. By way of illustration, the characteristics of a digital spool valve are theoretically and experimentally investigated. This paper also deals with the design of the controller and some concepts concerning the digital control of a valve, such as initialization, false protection, etc. An example is given to demonstrate the effectiveness of this digital control approach for a practical electro-hydraulic control system.

Hydraulic Spool Valve Metering Notch Characterization Using CFD

2003 ◽  
Author(s):  
Roger Yang
Keyword(s):  
Flow Characteristics ◽  
Post Processing ◽  
Hydraulic Oil ◽  
Simulation Procedure ◽  
Discharge Coefficients ◽  
Oil Flow ◽  
Computational Fluid Dynamics Cfd ◽  
Spool Valves ◽  
Spool Valve ◽  
Mode A

This paper presents some results from an attempt to characterize hydraulic oil flow inside spool valves with different spool metering notches using Computational Fluid Dynamics (CFD). Hydraulic spool valve oil flow under different conditions has been simulated using a commercially available CFD software program. The fluid flow is assumed steady-state, incompressible, isothermal and normally in a turbulent mode. A complete simulation procedure is presented from parametric geometry creation with a 3-D solid CAD program through final post-processing of CFD results. Main focus of this study is to explore the effects of geometric parameters of notches on important hydraulic oil flow characteristics, such as flow force and discharge coefficients. Formulas, intended for predicting such flow forces and discharge coefficients at different stage of spool notch openings, have been generalized and summarized under certain conditions based on a CFD result database from groups of same types of notches. Results comparison to experimental data is also presented.

The Development of an Electronic System for Industrial Control Purposes

1973 ◽  
Vol 6 (12) ◽  
pp. 489-492
Author(s):  
D. F. Nettell ◽  
W. J. Geers
Keyword(s):  
Control Systems ◽  
Integrated Circuit ◽  
High Performance ◽  
Closed Loop ◽  
Electronic System ◽  
Hydraulic Control ◽  
Industrial Control ◽  
Servo Valve ◽  
Performance System ◽  
Design And Manufacture

For some years the Authors' company has engaged in the design and manufacture of closed-loop hydraulic control systems. The hydraulics form a high performance system of considerable power. But the control is exercised electrically through the agency of a servo valve. This note describes the development of an electronic system for this application. Although originally rather specialised in purpose, the system has in the course of development become universal. Advantage has been taken of recent improvements in electronic techniques and at the time of writing the system is as advanced as any. Nonetheless, the speed at which electronics develops nowadays is such that some parts of the system may get outdated, and superseded. It has already happened once in the course of the work that a major invention the Integrated Circuit — has made obsolete an entire concept using discrete components before the development was complete. The same can happen again.

A Numerical and Experimental Methodology to Characterize the Gaseous Cavitation in Spool Valves with U-notches

2021 ◽  
Author(s):  
Emma Frosina ◽  
Gianluca Marinaro ◽  
Amedeo Amoresano ◽  
Adolfo Senatore
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Control Valve ◽  
Experimental Methodology ◽  
Area Of Interest ◽  
Sound Levels ◽  
Directional Control ◽  
Upstream Pressure ◽  
Spool Valves

Abstract The performance of spool valves can deteriorate and noise can occur due to cavitation. The noise sound levels caused by cavitation are influenced by many parameters, among which the most important is not-optimal geometry of components. In this paper, a 2 ways - 2 positions directional control valve was studied using experimental and numerical approaches. Tests were performed on a plexiglass body and steel spool analyzing the cavitating area that develops in U-notches. A dedicated test rig was equipped with a high-speed camera placed directly in front of the area of interest where cavitation occurs. Different working conditions were tested by varying the upstream pressure to encourage the development of cavitation. Images were acquired and post-processed, focusing the contour extraction between the liquid and gaseous phases. The images were compared with results from three-dimensional CFD numerical simulations performed using commercial software. The numerical estimation of flow characteristics corroborated the results from investigations carried out using a fast camera, including periodic cavitation structures. This study demonstrates the importance and usefulness of using a three-dimensional CFD approach during the prototyping phase to create quieter component designs.

Some Cavitation Effects in Spool Valve Orifices

1967 ◽  
Vol 182 (1) ◽  
pp. 163-174 ◽  
Author(s):  
D. McCloy ◽  
A. Beck
Keyword(s):  
Power Control ◽  
Control Systems ◽  
Mechanical Damage ◽  
Flow Coefficient ◽  
Flow Conditions ◽  
Discharge Characteristics ◽  
Hydraulic Equipment ◽  
Inefficient Operation ◽  
Spool Valves ◽  
Spool Valve

The existence of cavitation in hydraulic equipment leads to inefficient operation, mechanical damage, and vibration. The performance of valves in fluid power control systems is affected by cavitation. The spool valve finds numerous applications in this field and it is essential that these effects be thoroughly understood. In this paper a study is made of the occurrence of cavitation and its effect on the discharge characteristics of spool valves. It is shown that over a range of flow conditions cavitation has a profound effect on the flow coefficient.

Research of Static and Dynamic Characteristic Simulation and Experiment for the Sliding Valve

2013 ◽  
Vol 756-759 ◽  
pp. 4357-4362
Author(s):  
Rong Wu ◽  
Zheng Fei Yu ◽  
Ren Yang ◽  
Yan Jun Chen
Keyword(s):  
Structural Parameters ◽  
Experimental Tests ◽  
Static And Dynamic Characteristics ◽  
Control Signals ◽  
Simulation And Experiment ◽  
Dynamic Quality ◽  
Spool Valves ◽  
Opening And Closing ◽  
Spool Valve ◽  
Practical Implications

in the hydraulic and pneumatic system, spool valve is the spool component which is widely used in various types of control valves. Generally, valve spool, use fluid pressures as control signals, regulates the opening and closing of the pipeline, the pressure and flow of the system automatically. The spool valves static and dynamic quality impacts the system performance greatly. Researching its characteristic has practical implications to improve the performance of related products and optimize the system design. This article aims at researching the influences, on the static and dynamic characteristics of the sliding spool valve, caused by different structural parameters, through mathematical modeling, computer simulation and experimental tests.

Modeling Spool-Valve Flow Forces

2004 ◽  
Author(s):  
Noah D. Manring
Keyword(s):  
High Speed ◽  
Transient Flow ◽  
Control Valve ◽  
Hydraulic Control ◽  
Pressure Transient ◽  
Pressure Transients ◽  
Accepted Practice ◽  
The Stability ◽  
Spool Valve ◽  
Insight Into

This paper has been written to reconsider the important topic of transient flow forces that act on spool-type hydraulic control valves. Though this subject has been addressed and somewhat laid to rest many years ago, the high-speed applications of our present day require a fresh look at this topic for gaining deeper insight into the significant contributions that determine the stability and frequency response of the hydraulic control valve. Over thirty years ago, it became an accepted practice to neglect the pressure transient flow-forces acting on the spool valve as they were deemed to be minor compared to the velocity effects of the spool itself. In this paper, flow force models with and without the pressure transient term are compared and it is shown that the historic practice of neglecting pressure transients may no longer be valid. As a result, this paper provides justification for considering the pressure transients in the analysis and may provide an explanation for some of the discrepancies that have existed between theoretical expectations and laboratory results.

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