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.

Study of leakage flow through a spool valve under blocked-actuator port condition—Simulation and experiment

2013 ◽  
Vol 228 (8) ◽  
pp. 1405-1417 ◽  
Author(s):  
Milan K Mondal ◽  
Nirmal K Manna ◽  
Rana Saha
Keyword(s):  
Experimental Results ◽  
Radial Clearance ◽  
Leakage Flow ◽  
Pressure Sensitivity ◽  
Hydraulic Control ◽  
Leakage Flow Rate ◽  
Simulation And Experiment ◽  
Flow Through ◽  
Spool Valve ◽  
Hydraulic Control System

The spool valve is the key component of hydraulic control system, and the performance of spool valve depends on its leakage behaviour. Again, the leakage flow of spool valve is highly susceptible to valve uncertain dimensions, radial clearance and overlap or underlap. In the present work, the relative performance of critically lapped, underlapped and overlapped valves has been demonstrated in terms of leakage flow rate and pressure sensitivity about the metered ports. An approach to explore uncertain dimensions of the valve has been developed using CFD as an investigating tool. The comparison of CFD prediction against experimental results has also been carried out. It is found that the CFD predictions are in excellent agreement with the experimental results.

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.

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