A New Kind of Pilot Controlled Proportional Direction Valve with Internal Flow Feedback

Proportional direction valve is one of the most fundamental elements in electronic-hydraulic control technique. Its function is to control the operating speed, direction, position, and strength of output force of the hydraulic actuator continuously. Considering the different application and the cost, the existing technique mainly includes the internal feedback valve used in open loop system, and the electronic closed loop controlled valve used in closed loop system. Because of their different mechanical structure and the great different in performance, it brings inconvenience for customer to select, also inconvenience for enterprise to produce. Aiming at this problem, the idea of combining the above two kinds of valves into one body is proposed first, and then the new valve’s structure to realize this target is designed. The idea intends to apply the displacement pilot flow feedback control principle in present 2-position 2-way valve system to the proportional direction valve of 3-position 4-way system. Newly designed feed forward controller can decouple the interference between the internal feedback and the electronic closed loop. Redundant conversion is designed to electronic switch mode. Experiment on dynamic and static characteristic of new proportional direction valve in internal feedback control mode and electronic closed loop control mode is discussed to prove the new theory is correct. Although the new valve is of excellent dynamic response characteristic, its steady control characteristic in open loop control mode needs to be improved further. The research results prepare one new fundamental element for electronic-hydraulic control technology.

Output Characteristics of a Series Three-port Axial Piston Pump

Driving a hydraulic cylinder directly by a closed-loop hydraulic pump is currently a key research area in the field of electro-hydraulic control technology,and it is the most direct means to improve the energy efficiency of an electro-hydraulic control system.So far,this technology has been well applied to the pump-controlled symmetric hydraulic cylinder.However,for the differential cylinder that is widely used in hydraulic technology,satisfactory results have not yet been achieved,due to the asymmetric flow constraint.Therefore,based on the principle of the asymmetric valve controlled asymmetric cylinder in valve controlled cylinder technology,an innovative idea for an asymmetric pump controlled asymmetric cylinder is put forward to address this problem.The scheme proposes to transform the oil suction window of the existing axial piston pump into two series windows.When in use,one window is connected to the rod chamber of the hydraulic cylinder and the other is linked with a low-pressure oil tank.This allows the differential cylinders to be directly controlled by changing the displacement or rotation speed of the pumps.Compared with the loop principle of offsetting the area difference of the differential cylinder through hydraulic valve using existing technology,this method may simplify the circuits and increase the energy efficiency of the system.With the software SimulationX,a hydraulic pump simulation model is set up,which examines the movement characteristics of an individual piston and the compressibility of oil,as well as the flow distribution area as it changes with the rotation angle.The pump structure parameters,especially the size of the unloading groove of the valve plate,are determined through digital simulation.All of the components of the series arranged three distribution-window axial piston pump are designed,based on the simulation analysis of the flow pulse characteristics of the pump,and then the prototype pump is made.The basic characteristics,such as the pressure,flow and noise of the pumps under different rotation speeds,are measured on the test bench.The test results verify the correctness of the principle.The proposed research lays a theoretical foundation for the further development of a new pump-controlled cylinder system.

Mathematical Model of Hydrodynamic Torque Converter and Analytic Description of Streamline

The mathematical model of a 3-element centripetal-turbine hydrodynamic torque converter and analytic description of fluid flow inside the hydrodynamic torque converter are investigated.A new torus coordinate system is proposed so as to quantitatively describe fluid movement inside the hydrodynamic torque converter.The particle movement inside the hydrodynamic torque converter is decomposed into meridional component movement and torus component movement, and a universal meridional streamline equation is derived.According to the relationship between the converter wheel velocity polygon and its blade angle, a torus streamline differential equation is established.The universal meridional streamline equation is approximated with square polynomials.The approximation error curve is given and the percentage error is not greater than 0.86%.Considered as a function of polar angle, the blade angle cotangent of each converter wheel varies linearly with polar angle.By using integral calculus, torus streamline equations are obtained.As a result, the problem of difficult flow description of the hydrodynamic torque converter is solved and a new analytic research system is established.

Modeling,Simulation and Experiment of Electro-hydraulic Screw Down Servo System of Seamless Tube Rolling Mill

Electro-hydraulic screw down servo system(HSDS) is widely used in seamless tube rolling mill in western companies.But in Chinese companies,mechanical screw down system(MSDS) is popularly equipped and has a serious disadvantage that the roller would often be locked when it is overloaded.For the purpose of designing the first set of domestic twin-roller,four-cylinder and six-framework electro-hydraulic HSDS of seamless tube rolling mill,an experiment system that can simulate the process of seamless tube rolling is constructed.A digital simulation model of the experiment system is built with AMESim software and validated by comparing the simulation results with experiment results.The sudden load response of the screw piston position is studied with the built model and the experiment system.To improve the HSDS's positioning accuracy with large load,a hybrid control scheme of combining load disturbance feedforward compensation(LDFC) method based on servo valve's pressure-stroke feature and anti-saturation integral control(ASIC) is proposed.Both results of simulation and experiment indicate that the transient response time of the single-roller HSDS with the proposed scheme decreases from 0.65 s to less than 0.2 s without static error.To improve the system dynamic stiffness and production qualified rate,a flow rate feedforward compensation(FFC) control strategy based on oil compressibility to dynamic position error is proposed.This FFC strategy is validated with experiments in which the transient error caused by sudden load is reduced to less than 25% of that without FFC.By extending the simulation model to HSDS of a twin-roller,four-cylinder rolling mill,analyzing the mill deformation,and applying the LDFC,ASIC and FFC to the HSDS,the dynamic performance and positioning accuracy of compensated multi-roller HSDS at biting moment are predicted.The research results provide a theoretical and experimental basis for the design of HSDS of seamless steel tube rolling mill.

IMPROVE THE KINETIC PERFORMANCE OF THE PUMP CONTROLLED CLAMPING UNIT IN PLASTIC INJECTION MOLDING MACHINE WITH ADAPTIVE CONTROL STRATEGY

塑造被靠近的循环最新控制与的机器的塑料注射的夹钳的单位的运动特征开发了统一 reinvestigated 的两倍速度变量泵。就柱体等价物的宽变化而言，质量由夹钳单位和在关门的模子和开始过程期间在柱体上扮演的严重即时影响力量的传播比率引起了，参数和结构的一个适应控制原则被建议改进它的运动性能。在加速反馈获得和可变的团之间的适应关联被导出。压力微分反馈被介绍在小惯性和重影响负担的箱子中改进动态表演。到负担的和压力的改编被用来减少系统的精力损失。研究结果被模拟和实验验证。调查方法和结论对由传统的伺服泵单位控制的微分柱体系统也合适。

Minimum Curvature Design of Three-Element Centripetal-turbine Hydrodynamic Torque Converters

The influence of streamline bending inertia force on power loss is investigated.In order to analyze the combined effect of the inertia force and the path on the power loss,the accumulation effect expression of the inertia force on its path is derived.The calculation result shows that the accumulation effect of the unit inertia force on its path depends merely upon the velocity magnitude and the path scroll angle.As long as they are given,the accumulation effect is a constant and independent of the intermediate path.An important conclusion drawn is that the maximum inertia force rather than its accumulation effect plays a predominant role in the power loss.Thus,a new design method,minimum streamline curvature method,is proposed.Fluid particle movement inside a hydrodynamic torque converter can be regarded as curved movement on the circular surface and decomposed into a meridional component and a circumferential component.Each meridional streamline is designed to be close to a circular arc,while each torus streamline is constructed with a circular arc and a straight line segment.Based on the meridional streamline equation,the torus streamline equation and a streamlined thickness function,a blade surface equation of three-element centripetal-turbine hydrodynamic torque converter can be obtained.

Using Finite Element Analysis and Experimental Analysis on Vibration of a Piezoelectric Micro Pump

Due to the rise of biological and MEMS technology in recent years, some micro flow system components have drawn attention and been developed by many investigators. The importance of micro-pumps manufactured is higher than the other part of micro flow system since it is the power source of the entire micro-flow system and responsible for driving working fluid in the microfluidic system. In actual operation, the instability and bad dynamic characteristics of the micro-pump will cause larger fluid flow mobility error, such as transport behavior and response procedures failure, etc., and even damage the microfluidic system. Therefore, to investigate the stability and dynamic characteristics of a micro pump is necessary. The Finite element analysis (FEA), ANSYS Workbench, is employed to analyze the dynamic characteristics of this micro pump, and experiment is also considered in this study.

Quantitative Damage Detection for Planetary Gear Sets Based on Physical Models

Planetary gear set is the critical component in helicopter transmission train,and an important problem in condition monitoring and health management of planetary gear set is quantitative damage detection.In order to resolve this problem,an approach based on physical models is presented to detect damage quantitatively in planetary gear set.A particular emphasis is put on a feature generation and selection method,which is used for sun gear tooth breakage damage detection quantitatively in planetary gear box of helicopter transmission system.In this feature generation procedure,the pure torsional dynamical models of 2K-H planetary gear set is established for healthy case and sun gear tooth-breakage case.Then,a feature based on the spectrum of simulation signals of the dynamical models is generated.Aiming at selecting the best feature suitable for quantitative damage detection,a two-sample Z-test procedure is used to analyze the performance of features on damage evolution tracing.A feature named SR,which had better performance in tracking damage,is proposed to detect damage in planetary gear set.Meanwhile,the sun gear tooth-chipped seeded experiments with different severity are designed to validate the method above,and then the test vibration signal is picked up and used for damage detection.With the results of several experiments for quantitative damage detection,the feasibility and the effect of this approach are verified.The proposed method can supply an effective tool for degradation state identification in condition monitoring and health management of helicopter transmission system.

Research on Driver Fatigue Early Warning Method Based on ARM

Fatigue driving is one of the important reasons of road traffic accidents,fatigue driving is refers to the driver in a long time continuous driving or physical fatigue condition,and then come into being physiological and psychological function disorder. In order to overcome the limitation of single sensor in the fatigue test,aimed at the requirements of monitoring on the fatigue driving,this article designed an driver fatigue monitor system based ARM926EJ-S as a controller,it is used to determine the driver's fatigue and reduce the traffic acc ident. On the basis of fully considering the source correlation and complementary,it adopts the method of multi-source information fusion; by monitoring the pulse,heart rate,temperature of the human body,steering wheel grip strength to realized the fatigue level. The system of graphical interface adopts UCGUI. Finally,testing the main function modules of early warning system,the feasibility of the proposed early warning system is verified fusion.