The cylinder speed is controlled by the speed control valve in the circuit. The cushion valve affects the energy absorption of the cushioning device. For optimal cushioning and improved cylinder efficiency, two valves must be adjusted based on a specific openness relationship. A cylinder cushioning test bench is built to conduct experiments and find the corresponding relationship between the number of valve turns. An AMESim model simulates the cushioning effect at various valve openings. The sonic velocity discharge method measures the effective throttle area of pneumatic components, revealing the area matching relationship between the cushion valve and speed control valve when effective cushioning occurs. The results indicate that only certain openings of the speed control valve achieve effective cushioning, with the cushion valve adjustable within a narrow range, making precise adjustments difficult. The area matching relationship diagram helps enable quicker cushion adjustments.

Traditional flow control valves have disadvantages such as complex structure, large mass, and low output flow, and are not suitable for special fields such as aerospace. A new type of flow regulating valve has been designed, which is a rotary direct drive type and has the advantages of large output flow, simple structure, and light weight. Using UG software to create a 3D model, the working principle of the flow control valve is introduced. Based on Workbench and Fluent software, strength verification models and fluid domain models for flow valves are established, and simulations of valve core and sleeve deformation and steady-state flow field are conducted. The experimental prototype is processed and the static characteristics of the flow control valve are tested. The results show that the total quality of this flow control valve is 375.5 g, when the inlet pressure is 4 MPa, and the outlet pressure is 3.5 MPa, the maximum outlet flow rate is 25.99 L/min, which meets the needs of light quality and large outlet flow rate.

Under the environment of large-scale sea depth, the change of medium viscosity and the deformation of key parts of hydraulic system are obvious. For gear pump, the change of working medium viscosity and the deformation of parts will affect its volumetric efficiency. In order to study the change law of gear pump volume efficiency in deep sea environment, the mathematical model of sea depth and gear pump volume efficiency is established, and the volume efficiency of gear pump under different sea depth is analyzed by theory and simulation. The results show that the volumetric efficiency of gear pump increases with the increase of sea depth. When the sea depth reaches the limit of 11000 m, the influence of rotational speed and temperature on the volumetric efficiency of gear pump is more obvious than that on land. The research results provide a relevant theoretical basis for optimizing deep-sea gear pump and have a certain reference significance for the design of underwater hydraulic components and hydraulic system.

To address the issue of large fluid-induced vibration force and even serious local cavitation erosion damage caused by cavitation during the suction and discharge process of axial piston pump, the dynamic motion process of the piston pump is simulated using user-defined function and the dynamic mesh method. By conducting experiments on the cavitation flow-induced vibration characteristics of piston pump, the response characteristics of cavitation flow-induced vibration in piston pump are compared and analyzed, and the mechanism of cavitation flow-induced vibration in axial piston pump is obtained. The results show that the volume fraction of gas in piston chamber oscillates periodically with the change of cylinder angle, and cavitation phenomenon is mainly concentrated in the suction area of the pump; When the cylinder angle is in the alternating zone of suction and discharge, a negative pressure phenomenon occurs in the pressure field inside the piston chamber, and bubbles diffuse in the direction of the fluid jet, forming a clear local cavitation cloud.The frequency spectrum of cavitation induced vibration of piston pump coincides with the frequency spectrum of fluid pulsating load, directly affecting the amplitude of piston pump shell vibration and becoming the main cause of piston pump shell vibration response.

The energy recovery system of excavator slewing mechanism faces challenges such as a complex energy transfer structure and multiple conversion links. To address these issues, an axial piston motor with four assignment windows is proposed based on a double-motor active-passive composite drive slewing system for hydraulic excavator. This innovative design aims to streamline the energy transfer chain, minimize installation space, and achieve energy-efficient operation of the slewing system during both starting and braking phases. Based on the principles of kinematics of the piston motor and the dynamics of flow distribution areas, a parametric simulation model of an axial piston motor with four assignment windows has been developed in SimulationX. The simulation analyzes the influence of various structural parameters of the triangular slot in the port plate on the motor's flow pulsation and pressure impact. This analysis aims to identify optimal parameters for improved performance. Simulation results indicate that introducing a triangular slot in the port plate can effectively absorb and disperse flow pressure shocks. However, if the width or depth angles are too small or too large, significant flow pulsation and pressure shock may occur. The optimal structural parameters for the triangular slot are a width angle of 15° and a depth angle of 20°. These findings provide valuable insights for optimizing the design of the port plate in four port motor structures.

Due to the high-speed operation of the proportional servo valve and the flow state of the oil, the change of the hydraulic power is directly affected, then the dynamic and static performance of proportional servo valve and servo mechanism is affected. Therefore, in order to clarify the changing rules and characteristics of the flow force of the proportional servo valve, firstly, the theoretical mathematical model of flow force is established based on the orifice structure of valve core and valve body. Then, combined with the flow field simulation, the flow force changes under different openings and different pressure differences are analyzed, clear the deviation between the flow force simulation results and the theoretical results, revised mathematical model of hydrodynamic theory. Finally, based on the flow force test platform, the flow force changes under different openings and pressure differences are verified. The results show that the decrease of jet angle leads to the increase of steady-state hydrodynamics, the steady-state flow force power increases first and then decreases with the increase of valve opening. At the same time, the greater the pressure difference at the small opening, the greater the peak value of the steady state flow force. The research results will provide theoretical basis for nonlinear compensation control of proportional servo valve.

An adaptive adjustable dual-voltage controller is proposed to address the current issues of non adjustable driving voltage amplitude, unstable driving voltage, and large volume size in high speed on/off valve controllers. Firstly, to reduce the impact of input voltage's fluctuations of the controller on the accuracy of the output driving voltage, a voltage stabilization method combining the low drop-out linear voltage regulating technology and the built-in voltage closed-loop is proposed, which makes the steady-state error of the output voltage within 0.1 V. Secondly, the dynamic mapping function between the oil supply pressure and the critical opening/closing voltage is obtained through experimental identification to obtain the adaptive coefficient, which is used as the pulse width modulation duty cycle of the control voltage. Furthermore, low-pass filtering technology is used to achieve the average output of the adaptive voltage. Finally, a bistable parallel buck circuit and a double-sided circuit topology optimization method are adopted to reduce the volume size of the controller and achieve the maximum efficiency of heat dissipation. The results indicate that the developed adaptive adjustable dual-voltage controller can simultaneously achieve the operation of four high speed on/off valves above 100 Hz, with a linear duty cycle range of 0.3~0.7. Therefore, the proposed adaptive adjustable dual-voltage controller has the advantages of high dynamic performance, low power consumption, and strong scalability.

In order to study the lubrication and bearing characteristics of the textured piston pair of the water-based axial piston pump, the AMESim simulation model of the axial piston pump is established, and the correspondence between the reciprocating speed of the single piston, the length of the effective texture zone and its pressure characteristics in the cavity are obtained. Then the simplified CFD lubrication and bearing model of the texture piston pair is established, and the pressure maps, pressure distribution curves, and the bearing characteristics curves of the texture unit in a single cycle are analyzed. On this basis, the influence of the texture radius, depth and morphology on the lubrication and bearing characteristics of the piston pair is investigated. The results show that the bearing capacity curve of the piston surface is generally consistent with the pressure pulsation and pressure gradient curve of the piston cavity, and the bearing capacity is high in the high-pressure area, which shows a fluctuating downward characteristic corresponding to the pressure gradient curve. The bearing capacity of the plunger in the low-pressure area is relatively low. Under the simulation conditions, increasing the radius and depth of the texture helps to improve the bearing capacity of the piston surface, and the morphology of the texture has a greater influence on the bearing capacity, and the morphology of the bearing capacity from high to low is cylindrical, spherical crown, rhombus, square and triangle in the order of shape. In addition, the opening sizes of the converging and diverging wedges of the texture have a greater influence on the areas of the positive and negative pressure cores of the texture unit, and the cylindrical texture with a right-angle cross-section transition is more conducive to pressure agglomeration than the spherical crown texture with a circular cross-section transition.

As the main anti-fouling component of the aviation fuel system, the filtering characteristics of the double-layer square hole filter has an important impact on the reliability of the aviation fuel system. The CFD-DEM coupling method and visualization test are used to study the dynamic filtration process of the square-hole double-layer filter and the effects of flow rate and flow pulsation on the filtration efficiency of the filter. The results show that the accuracy of the double-layer filter is improved due to the influence of the supporting mesh. The surface medium filtration and the group of particles smaller than the mesh are the main forms of mesh blockage in the early stage of filter filtration. In the middle stage of filter filtration, a particle layer gradually forms. The flow rate has little effect on the filtration of the filter, and there is a slight fluctuation in the filtration efficiency of sensitive particles. The flow pulsation has a significant impact on the filtration efficiency of the filter. The larger the pulsation frequency and amplitude, the lower the filtration efficiency of the filter. The research results provide useful references for the design and selection of square hole filters.

Based on the demand for high-efficiency and high-precision dosing of raw materials in the composite propellant subgroups of solid rocket motors, a diaphragm metering valve with pneumatic control for precise dosing has been developed. Through AMESim software to build pneumatic simulation model, analyze in different spring stiffness, pneumatic force and hydraulic force under the joint action, the spool corresponding movement characteristics and response speed change rule. Using Fluent to simulate and analyze the liquid flow field area in the valve body, to obtain the mapping relationship between the hydraulic force of the spool and the pressure drop and flow rate in the circulation area under different pneumatic pressures of the liquid in the cylinder. Relying on the composite propellant sub-group feeding device, the weight change data of sub-feeding liquid material is measured by high-precision weighing scale to analyze the influence of the valve spool on the stability of sub-feeding liquid material under the action of multiple factors, and the relative error is found to be less than 15% by comparing and analyzing the simulation and experimental results of the export mass flow, which indicates that the simulation model can better characterize the flow characteristics of the accurate feeding diaphragm metering valve and lay a foundation for quantitatively taking raw materials of high-viscosity subgroups.

The motor-driven variable-speed axial piston pumps offer significant technical advantages and industrial value. A high-pressure axial piston pump for variable speed drive is developed, which adopts the structure form of cylinder body static, swash plate rotation, oscillating flow distribution, which can greatly reduce the friction of the three main friction vices in traditional piston pumps. The structure of this new piston pump is introduced, and a 47 mL/r pump prototype is developed to test the pressure, flow pulsation and volumetric efficiency of the pump. The results show that the new piston pump has a volumetric efficiency of 95%~98% and a pressure pulsation of 4%~8% when running at 200~1500 r/min, which has the advantages of a wide range of rotational speeds, high volumetric efficiency and small flow pulsation.

With the goal of reducing the flow force acting on the valve spool during operation, and using the external structural parameters of the valve spool as optimization variables,the method of optimizing the structure of the hydraulic servo valve spool is studied. The SPEA2 algorithm is utilized to optimize the external shape of the spool. The Pareto-optimal designs of the spool shape are obtained. The flow field and pressure distribution of the spool before and after optimization are simulated using CFD software, and the optimization effect is verified. An experimental platform is built to test the hydrodynamic force of the spool before and after optimization. This platform is capable of calculating the steady-state flow force acting on the spool during operation. Experimental results show that the flow force of the optimized spool decreases under different opening displacements, with an average decrease of 14.86% in the steady-state hydrodynamic force. The change trend is consistent with the simulation calculation, and the optimization effect is maximized when the opening displacement of the spool is 0.6 mm, further verifying the feasibility of the optimization scheme.

The high-frequency vibration rotary valve controls the opening and closing of the valve port by rotating the spool. The change of the opening degree and the reversal of the oil flow cause a change in the axial momentum of the oil, which generates axial flow forces that interfere with the stable operation of the vibration rotary valve. Based on the theoretical analysis of the high-frequency vibration rotary valve, the axial force mathematical model and the axial steady-state flow force equation of the spool are established. Through the simulation of Fluent, the flow field of the vibration rotary valve is analyzed by CFD, and the influence of pressure and axial opening on the axial steady-state flow variation is studied. Finally, the axial steady-state flow measurement platform is designed and built for experimental verification. The experimental results show that the axial steady-state flow force changes regularly with the change of the rotation angle of the vibration rotary valve, and the axial steady-state flow force generated by the inlet throttling is greater than that generated by the outlet throttling.

At present, the design or use of two-stage orifices are based on the flow calculation formula or empirical parameters of classic single-stage orifices, with significant selection errors. It is necessary to rely on on-site experiments to correct pressure loss parameters or use trial and error methods to replace orifices of different sizes for effect compensation. This research combines experiments and CFD simulations to investigate the influence of factors such as cavitation, different aspect ratios, and machining errors on the flow characteristics of two-stage thick orifices. The stable flow coefficients of orifices with or without cavitation are obtained for fixed length and different diameter sizes, providing a basis for the correct selection of two-stage thick orifices and the setting of characteristic parameters in mathematical modeling.

In response to the problems of poor reliability and outdated control technology of hydraulic controllable vibrator systems currently developed , the electro-hydraulic servo controllable vibrator is taken as the research object. ADAMS software is used to establish a system dynamics model, and MATLAB software is used to establish hydraulic and control system models, thus obtaining a co-simulation model of the system. The research uses iterative learning control method to improve the response performance of the system, improving the system's tracking accuracy of the desired signal. The simulation experiments show that the co-simulation model is correct and feasible, and the proposed control method can significantly improve the tracking performance and anti-disturbance robustness of the system.

To address the high precision temperature control requirements of semiconductor manufacturing equipment and other precision devices and instruments, a high precision temperature control system based on a temperature gradient attenuator is proposed. First, the heater is used as a temperature regulator to compensate for low-frequency temperature disturbances. Additionally, the flow mixing mechanism of the temperature gradient attenuator is employed to reduce high-frequency temperature disturbances in the fluid. Together, these components form a complementary high precision temperature control system. A simulation model is constructed using MATLAB/Simulink. Under model predictive control, disturbance attenuation analysis of the high precision temperature control system is conducted in both time and frequency domains. By comparing experimental and simulation results, it is found that the maximum temperature rise in the temperature control system using model predictive control is reduced by 24% during the temperature rise phase caused by thermal disturbances, compared to traditional PID control. The results validate the superior attenuation effect and disturbance rejection performance of the high precision temperature control system based on the temperature gradient attenuator.

As the core transmission system of drilling rigs, the dynamic performance of the rotary drilling system directly affects the operational reliability of the whole equipment. Aimed at the problem of subjective parameter setting and complex tuning in conventional PID controllers and fuzzy PID controllers, which leads to low control accuracy of feed speed and rotation speed in complex formation drilling processes of rotary percussion drilling systems, a control method based on particle swarm optimization (PSO) fuzzy PID is explored. Based on the working mechanism of drilling machine, the hydraulic transmission system of rotary percussion drilling is designed. The simulation model of rotary percussion drilling system is established by AMESim, and the rationality of the model is verified. The system coupling model of PSO fuzzy PID control is established by using the AMESim-Simulink-ADAMS co-simulation platform. The research results indicate that, compared with conventional PID control and fuzzy PID control under different loads, PSO fuzzy PID control can effectively reduce the overshoot of the rotary percussion drilling system, shorten the adjustment time, reduce the steady-state error. Moreover, the PSO fuzzy PID control has a certain inhibition effect on the oscillation phenomenon in the initial stage of the system. The PSO fuzzy PID control has better control accuracy and stability.

In order to meet the needs of ultra-clean flow control in semiconductor and other fields, a flexible diaphragm deformation field reconstruction technology based on magnetic film labeling is proposed. The magnetic film is used to track the deformation of the flexible diaphragm, then the mapping relationship between the magnetic film excitation space magnetic field and the deformation field of the flexible diaphragm can be established. Based on a long short-term memory neural network, the prediction model of the magnetic film magnetic field and deformation field is constructed, which achieves the reconstruction of the deformation field of magnetic film in different deformation states, thereby indirectly monitoring the operating conditions of the diaphragm. Additionally, training data samples are acquired through the COMSOL Multiphysics simulation platform, and the predicted deformation field data are analyzed by using the trained neural network model to validate the feasibility of the proposed approach.

Fluid-structure interaction vibration widely exists in hydraulic pipeline system. In order to study the influence of fluid flow and clamp constraint on the fluid-structure interaction vibration of pipeline, the pipeline is simulated by ANSYS Workbench software, and the experimental platform is established. The law between different flow rates and the vibration response of horizontal pipeline is analyzed by hammering method, and the influence of different clamp materials and constraint positions on the vibration characteristics of spatial pipeline system is studied. Simulation and experimental results indicate that as the fluid flow rate in the pipeline system increases, the inherent frequency of the system decreases. Changing the clamp materials and its constraint positions can effectively adjust the inherent frequency of the pipeline to avoid system resonance.

Position interference in valve-controlled cylinder systems during force tracking control, which jeopardizes control precision, is addressed by proposing a robust model predictive control strategy based on a linear matrix inequality convex optimization algorithm. The minimization performance index of standard model predictive control is transformed into an optimization problem that satisfies a set of linear matrix inequalities, followed by stability analysis. The robustness of the controller against system parameter uncertainties and its ability to suppress external disturbances are discussed within the framework of a discrete-time uncertain system with input/output constraints. Simulation results demonstrate that the proposed control strategy exhibits superior tracking performance and robustness compared to standard model predictive control under various frequency-based position disturbance signals.