scholarly journals CFD Simulation of a Post-Compensated Load Sensing Directional Control Valve

2021 ◽  
Vol 312 ◽  
pp. 05002
Author(s):  
Paola Fresia ◽  
Massimo Rundo
Keyword(s):  
Pressure Drop ◽  
Cfd Simulation ◽  
Control Valve ◽  
Design Tool ◽  
Lumped Parameter Model ◽  
Cfd Model ◽  
Load Sensing ◽  
Directional Control ◽  
Lumped Parameter ◽  
Directional Control Valve

The paper presents the CFD model of a load sensing directional control valve. The model was validated experimentally in terms of pressure drop and flow force at different positions of the spool. The spool position was imposed manually by means of a micrometric screw and a load cell was used for measuring the flow force. The CFD model was developed with the CAD-embedded tool FloEFD®. The model has been proved to be very reliable in estimating the pressure drop, moreover quite good results were obtained also in the evaluation of the flow force. The CFD simulations were used to tune the coefficients of a lumped parameter model of the valve, so that such a model can be efficiently used for the simulation of an entire hydraulic circuit. Moreover, the CFD model has been used as design tool for attenuating the detrimental effect of the flow force. In particular, the width of the land upstream of the metering edge has an influence on the resultant force on the spool. If was found that it is possible to significantly reduce the flow force at maximum opening with a relatively small increment of the pressure drop across the valve.

scholarly journals Research of stability of Load-sensing hydraulic drive operation, on the base of multimode directional control valve

2021 ◽  
Vol 12 (2) ◽  
pp. 93-99
Author(s):  
Oleksandr Petrov ◽  
◽  
Leonid Kozlov ◽  
Natalia Semichastnova ◽  
Olha Zavalniuk ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Energy Efficient ◽  
Hydraulic Drive ◽  
Control Valve ◽  
Design Parameters ◽  
Hydraulic Motor ◽  
Load Sensing ◽  
Directional Control ◽  
The Stability ◽  
Directional Control Valve

The article describes a new scheme of a hydraulic drive, which, thanks to the original design of a multimode directional control valve, has energy-efficient properties that are characteristic of load-sensing hydraulic drives. The proposed design of the multimode directional control valve ensures the operation of the hydraulic drive in four modes – unloading the hydraulic pump, regulating the flow of the hydraulic motor, the maximum flow of the hydraulic motor and protection against overload. In each of these modes, the hydraulic drive operates with low power losses due to the presence of a constant balancing pressure drop. This value is formed by a combination of design parameters of the directional control valve. The proposed value of the value of the balancing pressure drop of 0,7-0,8 MPa provides high energy efficiency of the hydraulic drive in the most critical operating mode – regulation of the hydraulic motor flow. In order to ensure the stability of the energy-efficient operation of the hydraulic drive in this mode, a research was made of the stability of transient processes with various combinations of design parameters of the overflow valve of the hydraulic control valve, as well as changes in the operating conditions of the hydraulic drive. As a result of theoretical researches, on the basis of mathematical modeling of working processes, combinations of design parameters of the hydraulic lock and the spool of the overflow valve were identified, which ensure the stability of the hydraulic drive in the mode of regulating the flow of the hydraulic motor. In particular, these are such parameters as the stiffness of the springs of the hydraulic lock and the overflow valve, the diameter and angle of inclination of the edge of the overflow valve spool, the area of the radial holes and the auxiliary choke of the overflow valve. It was also determined that in this mode, the stability of the hydraulic drive will be ensured under conditions of a load pressure of up to 20 MPa, a hydraulic motor flow rate of 100 l / min and a working fluid temperature of 80 °C.

Study on Static and Dynamic Characteristics of Load-Sensing and Pressure-Compensated Directional Control Valve

2013 ◽  
Vol 753-755 ◽  
pp. 2693-2699 ◽  
Author(s):  
Rui Lin Feng ◽  
Jian Hua Wei ◽  
Jin Hui Fang
Keyword(s):  
Transfer Function ◽  
Working Conditions ◽  
Dynamic Characteristics ◽  
Pressure Coefficient ◽  
Control Valve ◽  
Parameters Optimization ◽  
Static And Dynamic Characteristics ◽  
Load Sensing ◽  
Directional Control ◽  
Directional Control Valve

This study presents the static and dynamic characteristics of load-sensing and pressure-compensated directional control valve under the working conditions. A mathematical model is developed, two types of working conditions are presented through the static work point calculation. The static characteristic is analyzed by simulation, and the conclusion is validated by experiments. Solution procedure of the flow gain transfer function and flow-pressure coefficient transfer function is detailed introduced based on the above static computation, and their dynamic characteristic is analyzed by using Bode diagram. Finally, three types of compensatory modes are proposed, which provides very useful value and significance for the hydraulic component or system design and parameters optimization.

A Novel Pneumatic Non-Contact Suction Pad With Embedded Air Bearings

2010 ◽  
Author(s):  
Jyh-Chyang Renn ◽  
Chin-Yi Cheng
Keyword(s):  
Closed Loop ◽  
Cfd Simulation ◽  
Control Valve ◽  
Proper Function ◽  
Work Piece ◽  
Air Bearings ◽  
Directional Control ◽  
Gap Control ◽  
Application Fields ◽  
Directional Control Valve

In this paper, a novel suction pad based on CFD simulation and vortex levitation principle is proposed. To assure the absolute non-contact between the suction pad and the work-piece, four symmetrical air bearings are introduced and integrated into the design of the suction pad. In addition, the closed-loop gap control is applied to the operation of the suction pad, which avoids successfully the possible initial impact and maintains the desired gap between the suction pad and the work-piece. The vortex inside the suction pad serves to levitate the work-piece and the air bearings, on the contrary, try to push the work-piece away if the work-piece comes too close to the suction pad. Therefore, a proper function switching between the vortex and the air bearings is necessary. In this paper, a 5/3 pneumatic proportional directional control valve is utilized to switch these functions mentioned above. In the future, such a suction pad may find some potential application fields, like the pick-up and transportation devices for TFT-LCD, solar energy panels, etc.

Unsteady Flow Simulation of Directional Control Valve in Electro-Hydraulic Systems by Numerical Analysis

2014 ◽  
Vol 607 ◽  
pp. 382-385
Author(s):  
Aphaiwong Junchangpood
Keyword(s):  
Numerical Analysis ◽  
Pressure Drop ◽  
Real Time ◽  
Hydraulic System ◽  
Transient Flow ◽  
Pressure Coefficient ◽  
Control Valve ◽  
The Real ◽  
Directional Control ◽  
Directional Control Valve

The objective of the present paper is a numerical analysis of the transient flow through a 4/3 hydraulic closed center direction control valve. The real-time discharge coefficients corresponding to supply flow difference have been considered. In order to develop an intelligent control system for an electro-hydraulic system (EHS), a new controller has recently been proposed to control those parameters in a complex system. However, a mathematical model of the EHS including the transient parameters has not been clarified. The main objective of this paper is to numerically analyze the dynamic characteristics of the directional control valve and also the flow behaviors in the electro-hydraulic system control. Both the steady state and transient flow though the valve which affect to flow-pressure coefficient were numerically considered. Moreover, this paper presents numerical results, which explain the flow behaviors related with the real-time pressure drop and discharge coefficient. Both a high inlet flow and a large opening spool have determined the pressure drop increment.

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