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In recent years, power by wire (PBW) technique is developed in the European and American aviation field, and one of its important bases is electro-hydrostatic servo technique. In this paper, speed controlled and displacement controlled electro-hydrostatic actuation systems are modeled and simulated, by comparing their Bode graphics and time-zone respond curves, which shows that displacement control has small load inertia and high gain, so its dynamic performance is better. Thus, conclusion can be drawn that speed-displacement composite control may indeed improve the dynamic performance of electro-hydrostatic actuator.

Aiming at the problems of cavitation noise in the cone throttle valve, triangle groove cone throttle valves with 45, 53, 60 degree were selected as the research objects. Firstly the structure characteristics of the throttle valves were analyzed, then the three-dimensional models and mathematical models were established. By using the finite element simulation software ADINA, the simulation diagrams about pressure and flow velocity of the cone valves were obtained and then verified on the test bench which was about the noise characteristics of throttle valve. The investigation result showed that the flow field of the cone valve was complex, and there were local low pressure areas where were high incidence of cavitation; the valve with 60 degree spool had the minimum noise, which showed the best performance, then the 53 degree spool was a bit poor, and the worst valve was 45 degree spool. Increasing the angles of the triangle groove appropriately could reduce the cavitation noise and improve the performance of the valve. This investigation has great significance on understanding the flow field and controlling the cavitation noise in triangle groove cone throttle valves. Besides it also has a certain reference value to other hydraulic components on the cavitation noise control and structural optimization.

Hydraulic system is one of the most important parts of helicopter. Its function is to supply hydraulic power to the utilities. This paper studies an integration hydraulic system applied in helicopter flight control actuating system and simulates the system. The system has a small volume, light mass, meeting the requirements of helicopter control system actuating.

While axial piston pump is the core component of hydraulic system, its service life and reliability depend much on the selection of materials, friction pairs and process parameters. To identify these factors, wear condition of friction pair is conducted by using MWF-10 wear rig. Based on ANOVA of Taguchi Method,the influences of surface roughness and hardness on wear loss and friction coefficient are compared. In addition, the results show that the optimal friction pair and surface roughness of hard specimens have influence mostly on the wear loss and the friction coefficient.

The pair between slipper and swash-plate is an important friction pair in the axial piston pump. Due to quick relative velocity, alternating load, numerous slippers, and high contact pressure between the friction surfaces, the wear-out and fatigue failure constantly occurs, which is one of the key factors affecting reliability of the piston pump. It is of fundamental significance to investigate the mechanism of slipper power loss and to find an appropriate method to improve the lubrication of the slipper. Here, the model of friction power loss between slipper and swash-plate is established, and the friction power loss between slipper and swash-plate is solved and comparatively analysed. Finally, the correctness of theoretical analysis and simulation results are verified by experiments.

A new kind of hydraulic transformer, called variable hydraulic transformer (VHT), is proposed to control its load flow rate. The hydraulic transformer evolves from a pressure transducer to a power transducer. The flow characteristics of VHT, such as its instantaneous flow rates, average flow rates, and flow pulsations in the ports, are investigated. Matlab software is used to simulate and calculate. There are five controlled angles of the port plate that can help to define the flow characteristics of VHT. The relationships between the flow characteristics and the structure in VHT are shown. Also, the plus-minus change of the average flow rates and the continuity of the instantaneous flow rates in the ports are presented. The results demonstrate the performance laws of VHT when the controlled angles of the port plate and of the swash plate change. The results also reveal that the special principle of the flow pulsation in the ports and the jump points of the instantaneous curves are the two basic causes of its loud noise, and that the control angles of the port plate and the swash plate and the pressures in the ports are the three key factors of the noise.

The configuration and working principle of hydraulic hybrid vehicle (HHV) based on the hydraulic transformer (HT) were described to extend its energy-regenerated potential. The approximate algorithm of basic elements for pipeline distributed parameter model was summarized to simplify the pipeline model calculation, and the various basic elements of this method were proven to be used in the practical application by comparison with the experimentally validated Zhao and Hullender model. The pressure pulsation characteristics between the HT and accumulator of the HHV by considering Zhao model, Hullender model, and original pipeline approximate model was analyzed to optimize the system structure design by the method of the mathematical model, which mainly includes the series accumulator and parallel accumulator, respectively. The simulation result shows that the series accumulator was better than the parallel accumulator in terms of pulsation damping of hydraulic transformer with considering the pipeline effect. The test-rig result shows that the theoretical analysis of the pulsation between the HT and accumulator with pipeline was very close to the measurement data of the experiment in the curve trend, where the theoretical analysis results of pulsation characteristic for HHV were appropriate and reasonable.

To solve the low efficiency problem of hydraulic excavator, one type of Dual-Pump hydraulic architecture with combined Common Pressure Rail (CPR) and traditional valve controlled system is presented. Firstly, we analyze the energy consumption of excavator during one cycle to know the energy distribution among each actuator. Then, the Dual-Pump system is explained to design an easy to modify, cost efficient hydraulic hybrid excavator. Moreover, we focus on the boom system and construct the model. Finally, a simulation is created and the results illustrate that the proposed system can satisfy the design requirement.

In order to suppress the periodic interference of continuous rotary electro-hydraulic servo motor, make the motor tracking periodic signals more accurate, and improve the influence of friction interference on the performance of continuous rotary electro-hydraulic servo motor, mathematic model of continuous rotary motor electro-hydraulic position servo system was established, and the compound control method based on the discrete sliding mode controller was adopted to suppress the friction interference. Through the simulation, the result confirms that the discrete sliding mode controller decreases the tracking error of the system, increases the system robust performance and improves performance of continuous rotary electro-hydraulic servo motor. This method is simple and feasible.

In order to improve the low speed stationary of continuous rotary electro-hydraulic servo motor and avoid the pressure impact in the sealed cavity during the oil distribution, based on fluid and solid interaction theory, this paper adopted ADINA to analyze the pressure field distribution of sealed cavity in certain radial and axial gap, the computed model of the motor was established, and the pressure change of sealed cavity under the given dimension of the buffer groove was analyzed. The result shows that the pressure changes stably and buffer groove’s dimension is reasonable, which lays foundation for the structure design and experimental research of large displacement servo motor and improve the low speed performance of continuous rotary electro-hydraulic servo motor.

Direct drive volume control（DDVC）electro-hydraulic servo system has synthesized the advantages of high power of hydraulic system and flexible control of the motor. It also has other features such as energy saving, high efficiency, small bulk and high reliability. On the background for application to the ship steering system, DDVC electro-hydraulic servo system for the control actuator of ship is designed and the mathematic model is made and simulated with Matlab/Simulink. The steering gears closed-loop system’s simulation obtained the perfect dynamic performances; verify the correctness of the design with its control strategy. It can satisfy the ships request of boat to steering gears system and the DDVC electro-hydraulic servo system will be a extensive prospective power equipment of the control actuator of ship in future.

According to the running characteristic of an aircraft tractor and the specificity of serve target, the hybrid hydraulic system program is proposed. In the use of Adopting Simulated Annealing Genetic Algorithm, for the demand of aircraft tractor’s system, the multi-objective is transformed to a single objective function of the automobile’s dynamic performance and fuel economy performance by using the linear weighted method. Then the mathematical optimizing model of the powertrain is established, through calculating, reasonable parameters are gotten. The analysis of the simulation results shows that the comprehensive performance of the automobile has been remarkably promoted. On the basis of previous work, the system pressure of different weight aircraft models of traction has been optimized in order to give full play to the vehicle's performance. The research has important reference value for the theory analysis of hybrid systems and engineering applications.

Power chuck is an important component for machine tool. In order to solve the existing problem of oil-allocating for rotating hydraulic cylinder of power chuck, a new kind of rotating hydraulic cylinder based on hydraulic slipring is suggested. The deep circular groove oil film face seal technology is applied in the hydraulic slipring for oil transmission. Taking account of the vary of viscosity, the frictional torque of the seal face is simulated in detail. The experiment data prove the preciseness of the theoretical analysis. These theories provide reference for the practical application of the rotating hydraulic cylinder.

The parameter optimization for parallel hydraulic hybrid vehicle(PHHV) system has a significant impact on the vehicle dynamic performance, fuel economy and emission. In this article, several factors affecting system efficiency are used as the objective functions, system parameters are used as the independent variables, and the multi-objective optimization process is compiled in MATLAB. The process takes the ant colony algorithm as the optimization method, obtains the best system parameters through computing, and verifies the accuracy of optimization results through simulation.