\n The present research concentrates on the performance improvement of a two-stage proportional valve with internal hydraulic position feedback which is named as the Valvistor valve. In this paper, the performance constraint of this valve is identified and a novel electronic closed-loop control strategy with an integral-separation fuzzy proportional-integral-derivative controller is proposed to improve the valve performance, including the static characteristics and the dynamic characteristics. The results show that in the Valvistor valve, the comparison point and the feedback loop for the internal hydraulic position feedback is only in the main stage, while the input is in the pilot stage. This leads to the poor performance of this valve. The control strategy is very effective and the performance of the Valvistor valve is improved. With the control strategy, the error of the poppet displacement is reduced from 4.9% to 2.1% by adjusting the spool displacement in the pilot stage in real-time and the flow error is reduced from 5.3% to 2.3%. The dead zone of the poppet displacement and the flow is eliminated. The hysteresis is reduced from 5.3% to 2.6% and the linearity is improved. The overshoot is reduced from 0.06 to 0.02 mm and the settling time is reduced from 0.5 to 0.2 s. Moreover, the bandwidth is increased from 8 to 16 Hz.

Performance Improvement of a Two-Stage Proportional Valve With Internal Hydraulic Position Feedback

There are the problems of low flow control accuracy, small flow control difficulty, and limited flow range in the traditional pressure-compensation flow-control valve. For this, a method of continuous control pressure drop $\Delta p_{\mathrm {rated}}$ to control flow-control valve flow is proposed. And the precise control of small flow is realized by reducing the pressure drop $\Delta p_{\mathrm {rated}}$ . In the research, the flow-control valve with controllable pressure compensation capability (FVCP) was designed firstly and theoretically analyzed. Then the sub-model model of PPRV and traditional flow-control valve were established and verified through experiments respectively. Finally, the accurate co-simulation model of the FVCP was established. The continuous control characteristics of pressure drop $\Delta p_{\mathrm {rated}}$ , the flow characteristics of FVCP, and the influence of different parameters $d_{2}$ were studied. The research results demonstrate that, compared with the traditional flow-control valve, the designed FVCP can adjust the compensation pressure difference in the range of 0.3 ~ 1.7 MPa in real-time. And the flow rate can be altered within the range of 44% ~ 100% of the rated flow. The diameter $d_{2}$ of the console shoulder has almost no effect on the compensator operating characteristics.

/pdf/design-and-analysis-of-a-flow-control-valve-with-1vnchxnksi.pdf

Design and Analysis of a Flow-Control Valve With Controllable Pressure Compensation Capability for Mobile Machinery

Hydraulic control valves are widely used in industrial production, agricultural equipment, construction machinery, and other large power equipment for controlling the pressure and flow of fluids in hydraulic systems. The driving method has a significant impact on the response and control accuracy of hydraulic valves. This paper reviews the driving methods of spools from five aspects: solenoid drive, material expansion drive, motor drive, hydraulic valve drive, and another drive. It summarizes the various schemes currently available for spool drive and analyzes each of them. After optimizing the driving method of the valve core, the control accuracy can reach 3%, and the minimum response time is 7 ms. According to the characteristics of the different drive methods, the differences between them are compared, the advantages and disadvantages of each drive method are analyzed, and the application scenarios for each drive method are identified. Solutions to the drawbacks of the existing drive methods are proposed, which provide directions for further optimization. We have found that solenoid drives are simple to control, low cost, and the most widely used. Material telescopic drives, motor drives, hydraulic valve drives, and other drives are costly, complex to control, and optional for use in special requirement situations. Based on the existing spool drive methods, an outlook on future drive methods is presented. This review facilitates a comprehensive understanding of the drive methods of hydraulic valve spools, points out the shortcomings of the existing drive methods, and is of great significance in improving the existing drive methods and proposing new drive methods. This paper has a positive effect on improving the control accuracy and responsiveness of hydraulic valves. 

Review of Recent Advances in the Drive Method of Hydraulic Control Valve

\n Compared to conventional globe valves, the pilot-control globe valve (PCGV) possesses advantages of lower energy consumption and higher space utilization. In order to analyze the effects of pilot pipe and damping orifice arrangements, this work proposes four PCGVs and conducts simulations to compare their overall performances, overall flow characteristics, and local flow characteristics around the valve core. In general, the arrangement of the pilot pipe has larger effects on the hydroperformances of PCGVs than the arrangement of the damping orifice. The pipe-parallel-mounted type PCGV performs better in hydroperformance than the pipe-perpendicular-mounted type PCGV, and thus is recommended in practice. As the specified valve core travel increases, the flow resistance of PCGVs decreases and the flow capacity of PCGVs increases. However, overlarge specified valve core travel has little effects on the flow resistance and flow capacity of PCGVs. Besides, the increased specified valve core travel could effectively reduce the wear induced by the uneven pressure distribution on the external lateral face of valve core, but it has little effect on the wear induced by the uneven pressure distribution on the bottom face. For all pipe-perpendicular-mounted type PCGVs, the variation of axial force imposed on the valve core relative to the specific valve core travel presents similar tendencies under different incoming flow velocity within the scope of the investigation, which could be concluded into a fitting equation. This work could be referred for the optimization of PCGVs and other similar valves.

Pilot Pipe and Damping Orifice Arrangements Analysis of a Pilot-Control Globe Valve

This investigation utilized binary-coded, parallel-connected on-off valves that can achieve high flow rates with fewer valves while addressing flow peak challenges. By considering temperature and refining modeling techniques, the study rectifies certain limitations observed in previous research, such as neglecting temperature, imprecise valve orifice flow coefficients, and absent flow pattern visualization, thereby enhancing flow prediction accuracy. The results for the ML_CFD-based model suggest that although extrapolation challenges exist in rarely data-driven systems, the proposed approach exhibits errors under 5 % across diverse metrics, attributable to the effectiveness of well-constrained overparameterized models and the segmented structure of digital flow control units. On the other hand, while the simplified Hybrid Analytical model shows minor deviations and offers easier implementation, it encounters constraints when processing data beyond its pre-tuned coefficient of discharge values. 

Evaluating the performance of machine learning CFD-based and hybrid analytical models for transient flow prediction in temperature-compensated digital flow units

The present study is focused on the construction of a well-performing pilot controlled proportional flow valve with internal displacement-flow feedback. A novel control strategy for the valve is proposed in which the flow rate through the valve is directly controlled. The linear mathematical model for the valve is established and a fuzzy proportional–integral–derivative (PID) controller is designed for the flow control. In order to obtain the flow rate used as feedback rapidly and accurately in real-time, back propagation neural network (BPNN) is employed to predict the flow rate through the valve with the pressure drop through the main orifice and main valve opening, and the predicted value is used as the feedback. Both simulation and experimental results show that the predicted value obtained by BPNN is reliable and available for the feedback. The proposed control strategy is effective with which the flow rate through the valve remains almost constant when the pressure drop through the main orifice increases and the valve can be applied to the conditions where the independence of flow rate and load is required. For the valve with the proposed control strategy, the nonlinearity is less than 5.3%, the hysteresis is less than 4.2%, and the bandwidth is about 16 Hz. The static and dynamic characteristics are reasonable and acceptable.

A Novel Control Strategy for Pilot Controlled Proportional Flow Valve With Internal Displacement-Flow Feedback

The invention discloses a port plate structure of a three-oil hole axial plunger pump. The port plate structure of the three-oil hole axial plunger pump is characterized in that a vibration damping oil hole in a non-dead center transition region and a vibration damping oil hole in a top dead center transition region communicate with each other through an oil channel; and when the pump operates, high and low-pressure oil of the two vibration damping oil holes can communicate with each other. The port plate structure has the advantages that the phenomena of oil trapping, pressure impact, and the like, in a plunger in the transition region are avoided, noise of the pump is reduced, the leakage amount of the pump is decreased, efficiency of the three-oil hole axial plunger pump is improved, and the purposes of energy conservation, environment protection and eco-friendly production are achieved.

Port plate structure of three-oil hole axial plunger pump

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A Novel Control Strategy for Pilot Controlled Proportional Flow Valve With Internal Displacement-Flow Feedback

Port plate structure of three-oil hole axial plunger pump