The numerical and experimental research on the flow behavior in the angle – seat valve with different connection modes is conducted. The RNG k-ε turbulence model and the standard wall function are used to calculate the internal flow filed. In comparison the experimental and numerical results of flow coefficients, the accuracy of the mathematical model and calculation method is verified. The results showed that: the angle-seat valve has better flowing performance and the larger area of flowing core region under the positive connection. Moreover, the big swirl exists on the underside of valve outlet will lead to the increase of flow resistance. The secondary flow both occurs on the cross section of valve spool under both connection modes. The positive connection mode has higher flow instability.

In view of the reality of the pneumatic control precision is not high and stagnation defects existed in the manipulator, in order to realize the trajectory tracking of pneumatic manipulator better, reduce the nonlinear of the PID+ESO controller, through the analysis of principle, use PID control and extended state observer PID under the control of the pneumatic manipulator is studied by the controller. Design on MATLAB/simulink were performed on the simulation, the simulation curve and error curve, this controller principle is applied to the pneumatic test rig, the error based on extended state observer PID controller is low, that is applied to coordinate the pneumatic manipulator with fast response speed, high control precision.

A kind of new double-bladder accumulator is introduced with the purposes of improving dynamic performance, suppressing pulsation noise and moderating pressure shock. The differences of dynamic performance between the double-bladder accumulator and the old one are analyzed. The generalized Maxwell model of double-bladder accumulator is deduced, and the internal relations between the model parameters and dynamic performance are analyzed. The simulation analysis shows that the double-bladder accumulator’s abilities of suppressing pulsation noise and moderating pressure shock are better than the old ones. The structure of double-bladder accumulator provides more chooses for adjusting the hydraulic control system.

In order to analyze the change of internal flow field of cotton picker fan under actual working conditions. Use the method of FLUENT numerical simulation analyze the internal flow. Through compare the influence of different speed and flow rate conditions on the velocity field and suction pressure. The result shows :with the increase of the speed, the fan outlet speed and the maximum transportation speed are increasing, and the suction negative pressure is increasing；With the increase of the flow rate, the air outlet speed and the maximum transportation speed are increasing, and the minimum suction negative pressure decreases and the maximum value increases. This conclusion for the actual working conditions of cotton fan have a clearer understanding, and lay a basis for the structure optimization.

Coanda ejectors are the objects to be studied in terms of the influence of the ratio of fluidic width and wall curvature on the performance. The model which utilizing the Coanda effect is established. The influence of the ratio of fluidic width and wall curvature on the effectiveness of jet attachment is studied. Furthermore, the simulation analysis is carried out to study the flow-field distribution inside the ejector. Meanwhile the experimental tests of the Coanda ejector are carried out. The influence of the ratio of fluidic width and wall curvature on the performance of the Coanda ejector is analyzed from both the vacuum degree in the outlet area and the vacuum response time. The result shows that when the ratio of fluidic width and wall curvature is around 1/50 the working performance of Coanda ejectors is optimal. The final vacuum is 0.056 MPa and the vacuum response time is 0.2 s.

The kinematic analysis of a parallel robot with six degrees of freedom is presented. A new position position solution is presented based on the analysis of the local coordinate transformation matrix. Based on the position forward solution algorithm, a closed loop control strategy for 6-DOF platform is proposed. The control strategy is simulated and analyzed by Matlab/Simulink. Under the step input signal and the sinusoidal input signal, the dynamic characteristics of the system is well.

A hydraulic buffering valve for vehicle shift is an important part of the electro-hydraulic automatic mechanical transmission. It can make the vehicle speed smoothly transit during vehicle shift. In order to design a satisfactory hydraulic buffering valve, it is necessary to study the appropriate optimization method. A simulation model of hydraulic buffering valve for vehicle shift is established based on AMESim. The influence degrees of the various structural parameters of hydraulic buffering valve are analyzed on the characteristics of the object through design of experiments (DOE). Optimum values of the main structural parameters are obtained by genetic algorithm. The feasibility of the optimization method is verified by the experimental platform.

valves are the key components of the fluid transport system. It is important to get its conditions and performance accurately for safety and reliability of the system. In this paper, a study of condition monitoring and performance evaluation is given based on high pressure pneumatic ball valve. The condition monitoring test system is constructed. The data are got by a test. The performance of the value is evaluated via the inlet and outlet pressure and the rotation angle of actuator. Experimental results demonstrate that the transient and the stable features in ball valves working process can be well combined to evaluate the performance.

Against the test cost highly and the development period long of the four assignment window axial piston motor,a simulation and test method is proposed to construct the virtual prototype of the four assignment window axial piston motor.Firstly, It’s necessary to bulid the 3D dynamic model by RecurDyn and the 1D hydraulic system model by AMEsim based on real physical model of the four assignment window axial piston motor;Next,the part of the geometric models should be performed modal analysis by ANSYS,in this way,the multi-flexible-body dynamics model based on R-Flex could be built in RrcurDyn;Then,using the interface technology between RecurDyn and AMEsim,the information about the parameters required when co-simulation is called could be communicated and shared in real time,so it is achieved to construct the virtual prototype .Finally, through solution of multi-flexible-body dynamics in RecurDyn, the dynamic stress-strain of the four assignment window axial piston motor is obtained under different working conditions, the co-simulation and test is achieved by the virtual prototype of the four assignment window axial piston motor,it provides important reference and gist for experimental study,characteristic analysis,structure optimization and prediction of fatigue reliability,etc.

In order to solve the problem of cotton have a poor discharge into the fan. This paper takes a newly developed fan for small cotton picker as the object of study. The fan model is established by field measurement data and UG software. ICEM software is used to mesh it, and the internal flow field is simulated by Fluent software. It can be seen from the simulation results :The static pressure distribution on the impeller wall is uneven, and the static pressure of the impeller wall near the outlet is obviously larger than the remaining part.; The gas flow rate decreases gradually along the direction of the outlet as the impeller rotates. There are obvious vortices in the impeller passage, and backflow occurs at the outlet. The simulation results of the optimized fan can be seen: The swirl in the impeller runner disappears obviously, and the backflow at the outlet disappears. The problem of poor cotton emission has been effectively solved, and the internal flow field of the cotton picker fan has been greatly improved. It provides a certain theoretical basis for the optimization of the structure of the cotton picker fan.

Three freedom flotation platform for weightlessness simulation of docking control equipment is designed for a full physical simulation of a space docking control device. Through the design of the platform air float function and motion function, determine the working principle and component selection of the air control system; In terms of structure, pay attention to the smoothness of movement and modular, integrated design, the use of hierarchical layout of the frame structure, to ensure that the center of gravity in the horizontal plane projection direction and horizontal geometric center as close as possible. The flotation platform prototype is tested to meet the needs of the tested equipment, to ensure the design idea is correct. It has some reference value for the design of multi-degree of freedom air float system for simulated weightlessness test.

This paper introduces the pneumatic hydraulic launching system, based on accumulator and hydraulic motor driving UAV; Then establishes the mathematical model of the main parts of the system, and builds the simulation calculation model by AMESim, to evaluate the effect of dynamic friction on speed of the UAV. At last the end ejection velocity of dynamic friction curve is fitted. After the simulation, a prototype experiment is conducted. The dynamic friction and the coefficient of friction for dynamic contact are measured, which provides a reference for the simulation, design and manufacture of pneudraulic launching system of UAV.

In this paper, the machine performance of a water hydraulic piston pump used the 17-4PH/CFRPEEK and 1Cr17Ni2/CFRPEEK as the piston pairs is studied. The sizes of the piston and cylinder sleeve are measured before and after the tests. The tribological properties of the two kind of pairing materials are investigated. The results show that the efficiency of the pump using 1Cr17Ni2/CFRPEEK as piston pairs is higher than that using 17-4PH/CFRPEEK as piston pairs. The abrasion resistance of 1Cr17Ni2 is better than that of 17-4PH when paired with CFRPEEK. In addition, the abrasion resistance of the CFRPEEK cylinder sleeves is better than that of the 1Cr17Ni2 or 17-4PH pistons. Generally, the 1Cr17Ni2/CFRPEEK shows better tribological performance than 17-4PH/CFRPEEK in the water hydraulic piston pump.

The tribological properties of Al2O3, SiC, Si3N4, ZrO2 and 17-4PH were investigated by pin-on-disc friction test for seawater pump in the seawater environment. The experimental results show that the friction coefficient and wear of ZrO2 coupleing with 17-4PH with heat treatment are the lowest of four kinds ceramics, the surface is the most smooth and easy to form hydrodynamic lubrication. Therefore, compared with the other three materials, ZrO2 and 17-4PH are more suitable as a micro-surface contact pair material.

Using AMEsim software to build the mathematical model of grooved vane pump, the characteristics of the pouring flow when the pressure is drop are obtained. The pressure pulsation rate is reduced to 0.05% by using the method of precompression and the pump's outlet flow is compensated to the transition zone, and the phenomenon of pressure drop when the low pressure oil is connected with the high pressure oil is basically eliminated. By using some devices that detect pressure and adjust the pressure amplitude, the pump becomes a closed-loop system that can adaptively adjust, the pressure pulsation of the flow of is always kept very small under varying loads.

Abstract: Though the theoretical teeth profiles of the chordal rotating-pair do not match the condition of mutual conjugation, they still keep in touch with center line every moment. A new type cosine rotator pump separated by roller was proposed according to that theory, with equidistant curves of theoretical teeth profiles instead of actual ones. The?new method can guarantee that only one pair of gear teeth contacts at one point, which radically eliminates the situation of oil trapped.?Besides, the mode of surface contacted friction changes from sliding to rolling, drastically reducing the friction force.Then the formula was derived to illustrate that the momentary flow rate of the new pump maintained approximately constant in the method of symbolic-graphic combination. Based on the results of analysis on the liquid pressure, the meshing force and the resultant of radial force, three methods were concluded to reduce the radial force effectively, which were choosing proper width and top diameter of rotator, reducing size of outlet pumping chamber and using hydraulic balance. What this article discussed may provide theoretical references for the further study to put the new pump into practical function.

Abstract: The new load simulator achieves loading of steering Gear with the theory of friction torque load. Based on the principle of friction and abrasion, a new calculating model of friction torque is established for diminishing error, and the usability of the calculating model is confirmed through three example applications, including the ring friction disk, discal friction disk and flabellate friction disk. The temperature field on disk of simulator is established based by using ABAQUS. It is analyzed what the relation of pressure and speed with field. The simulation results show that the tem-perature rises at elevated pressure and speed, besides, it make the high temperature section more focused. The field is more sensitively with speed increase than pressure increase. The flabellate friction disk is more suited to loading of small torque than the ring friction disk.

With the fore-valve compensating, LS system is not able to distribute the flow proportionally according to the throttle-opening of multi-way valve of every actuator under the condition of flow saturation, which affects the coordination of the actuator’s compound action seriously. So this paper proposes a method to achieve anti flow saturation of the system by flow calculation. On this basis, the anti-flow saturation model of the LS is built in the AMESim whereby the analyzing is made. The conclusion of the simulation shows that when it adopts flow calculation, the LS system can still distribute the flow proportionally according to the throttle-opening of multi-way valve of the every actuator under the condition of flow saturation, so that the coordination of compound action is guaranteed. What’s more, it can provide theoretical reference for solving the practical problem of flow saturation of the LS system.

Abstract: In the electro hydraulic servo loading system of the fatigue life and performance evaluation testing machine for aviation joint bearing, the ADRC is designed to evaluate the state information and disturbance information of the system, to solve the problem of precise control of dynamic load spectrum under extreme conditions and without disturbance. By simulation and experiments, proved that ADRC controller control effect is better than PID control in the electro hydraulic loading system with the same external conditions, the response speed, anti-interference ability and robustness of the system are improved significantly.

As the hydraulic impact problem of coal mine hydraulic support system,we design a new large flow and high-water proportional directional valve.This paper introduces the structure and working principle of the valve and uses AMEsim simulation software to build the simulation model.It is found that in the case of ramp signal input,this valve can realize normal direction and the main valve port opening size is determined by the input signal;in the case of step signal input,the stability of the valve is verified through AMESim and the influences of the damping diameter and the taper at the end of the main spool on the dynamic characteristics of the valve was analyzed.Fast response of the valve is impacted by the damping diameter and the stability of the valve can be improved by selecting the taper at the end of the main spool.

IN order to analyze the working performance of a DCT's hydraulic control system at different working conditions, using AMESim software to calculate the shifting force and the outlet flow of lubrication cooling subsystem, then through the bench test of DCT to verify the calculation result. The calculation and experiment results are coincidence and indicate that VBS valve can accurately control the shifting force, and DCT's hydraulic control system can rapid perform shift. In addition calculate the influence of oil temperature on shifting force by the computation model of DCT hydraulic system. The calculation result indicate that oil temperature at 30~90℃ have little influence on shifting force .

In order to solve the flow mismatch problem between pumping source output and workload demand and based on the PCM control in the concept of digital pump, this paper introduces a configuration approach suitable for D+A combination controlled multi-pump hydraulic system in forging hydraulic press. The multi-pump source flow can be regulate continuously and in real time, due to the system is with the characteristic of volumetric speed control, which could solve the poor efficiency problem in the hydraulic system. Besides, a time delay control strategy is proposed to reduce the instantaneous flow impact when the pumps unit state changes. Simulation results shows that the degree of flow impact can be reduced by 50%-75% via the proposed control strategy.

A new type of hydraulic plunger pump was introduced in this paper. The plunger which could not only rotate but also reciprocate was developed by the utilization of the two-motions-freedom of a single spool, which could pump oil while distributing oil. The pump had the advantage of simpler configuration, higher max speed, better efficiency and higher pressure than old type of hydraulic plunger pump with valve plate and sliding shoes. The test showed that the pump had a better performance on losing weight, increasing rotation speed and raising pressure.

In order to improve the position tracking precision, a 2-DOF (degree-of-freedom) hybrid control strategy combined a three variable feedback controller and an inverse model feed-forward controller is proposed for an electro-hydraulic shaking table, which can also solve the problems caused by the small inherent frequency and the damping ratio of the electro-hydraulic system. The acceleration and speed feedback signals are employed to the position closed-loop system to improve the inherent frequency and the damping ratio of the hydraulic actuator in the three variable control, which is used to ensure that it can expand the system working frequency bandwidth under the condition of system stability. In order to further expand system bandwidth, an inverse model feed-forward controller is employed to improve the dynamic response performances and the position tracking precision of the experimental system. Experimental results show that the proposed 2-DOF hybrid control strategy is effective to the electro-hydraulic position servo system.

Position-pressure Master-slave Control is a new method for the Electro-hydraulic Servo System of valve controlling cylinder based on Master-slave control theory.In this paer , the valve controlling cylinder position control formula is established , compensating the transformed signal into the master position closed loop of the electro-hydraulic servo system, which could achieve the position-pressure master-slave control by collecting the pressure signal from rear and rod cavity of hydraulic cylinder, meanwhile, then applling position-pressure conversion formula to turn dynamic pressure signal into a position signal, Analysis of the control effect of this method by building the simulation models in MATLAB/Simulink software and the simulative results show that the control method is correct, effective and feasible. The results indicate that the proposed method can achieve online converting between position and pressure and improve the response speed and control precision of the system through collecting the position and the pressure signal when field prototype straightening steel plates, which also provide theoretical basis to design and research of other electro-hydraulic servo system.

Abstract: As an important part of aircraft hydraulic system, the hydraulic pipe is an important guarantee for the safe flight of the aircraft. Due to the complexity of the flight environment, the fatigue analysis under random vibration loading is an important means of aircraft hydraulic pipe dynamic design. The paper selects a typical hydraulic pipe of the domestic large passenger aircraft C919 left wing as the research object, the ABAQUS finite element software is used to random vibration response analysis, and obtains stress response power spectral density function under random vibration loading, strength characteristics of hydraulic pipe under the random vibration load is analyzed, and combined with the S-N curve to estimate the fatigue life of the dangerous parts of the structure, provides a theoretical reference for the design and optimization of the Aviation Hydraulic Pipeline.

Water hydraulic proportional/servo valve, which controls the speed and direction of actuator, is the key control element of water hydraulic actuated automation equipment. A novel rotary spool proportional valve is developed, and the composition, the working principle as well as the features of the design are described. A model is built and numerical studies are carried out to investigate the dynamic characteristics, especially the frequency response and the stability of the valve. The results show that: (1) Reduce the radius of the spool and the valve sleeve with the length, or increase the gap between the spool and the valve sleeve appropriately, can improve the stability and the response frequency of the system; (2) Torque constant and rotational speed constant of torque motor can affect the stability and response frequency of the system. This research provides a basis for developing high performance water hydraulic proportional/servo control elements.