This paper introduces the development of the hydraulics hydrodynamics pneumatics seals industry from four aspects: the main achievements of industry development from 2012 to 2022, the operation situation of the industry in 2023 and the outlook for industry operation in 2024, the main issues that need to be paid attention to in industry development, and the current main tasks of the industry.

Reciprocating sealing performance is a key factor affecting the efficiency, reliability and safety of mechanical equipment. With the need of reciprocating seal design and the complexity of practical application environment, the theoretical research of reciprocating seal is becoming increasingly important. Based on the research status of numerical simulation and Simulation of reciprocating seals, this paper expounds in detail from three aspects: the research of mechanics and elastohydrodynamics, the research of transient effect and thermal effect, and discusses the existing problems.

As the core components of all kinds of high-end equipment, the working reliability of ultra-high pressure mechanical seal has an important impact on the improvement of equipment efficiency and operation life. In this paper, the working parameters and research objectives of ultra-high pressure mechanical seals are introduced, the types and characteristics of ultra-high pressure mechanical seals are analyzed, and the corresponding countermeasures are put forward according to the problems faced by ultra-high mechanical seals.

The pressure pulsation generated by the axial piston pump is one of the reasons for the instability of the hydraulic system. Pressure pulsation can cause vibration and fatigue failure of the system, and even damage the components causing great losses. The pressure pulsation of the plunger pump is mainly due to the motion flow generated by its motion mode and the dynamic flow caused by its own structure under the action of impedance. This paper mainly introduces and discusses the research of domestic and foreign researchers in this field. This includes the causes of pressure pulsation, measurement methods, the effects of various factors on pressure pulsation and optimization schemes, and the placement of active and passive pulsation controllers outside the pump structure. As a basis for further research on piston pump pressure pulsation.

Aiming at the leakage problem in a domestic piston combined seal ring, this paper simulated the deformation and contact stress changes in the assembly process of piston combined seal ring based on ANSYS Workbench, and simulated the effect of medium pressure on the elastomer of seal ring by the loading method of fluid pressure osmotic load. The effects of compression rate, hardness and working pressure of elastomer of piston combined sealing ring on its sealing performance were studied. The results show that the maximum contact stress of the upper and lower sealing parts of the elastomer (BC section, DE section) is slightly less than the sum of the working pressure and the maximum contact stress of the elastomer under assembly, and the sealing performance is good. The greater the compression rate and hardness of the elastomer, the greater the maximum contact stress. Through the study of opening clearance and opening Angle of piston combined seal ring, it is concluded that the small thickness of the retaining ring and the large opening clearance of the guide ring are the main reasons for the leakage in the piston combined seal ring. The test results show that the piston combined sealing ring made of hydrogenated butanyl (HNBR-80) elastomer, polyester elastomer (TPEE) retaining ring and nylon (PA66) guiding ring meet the requirements of hydraulic cylinder of a certain equipment.

In view of the large overflow loss in the rotary system of a medium-sized positive flow excavator of XCMG, an energy-saving control method to reduce energy loss is designed. Firstly, the model of the key components of the excavator rotary system is established, secondly, the sliding mode controller is designed based on the proximity law, the parameters of the approach law are determined according to the fuzzy rules, and finally the pump displacement is changed according to the pressure of the motor relief valve to achieve the rapid response of the pump output flow to the pressure, so as to achieve the purpose of energy saving and consumption reduction. After simulation analysis, compared with the traditional open-loop control and PID control of the excavator, the pump output flow under the fuzzy sliding mode control is significantly reduced, and the motor speed does not change much compared with the previous two algorithms, which will not reduce the efficiency of the rotary operation, and it can be seen that the designed algorithm is effective.

In view of the skidding phenomenon of aerial work platform under severe working conditions, and the problem of engine speed loss when turning at high speed, the research is carried out from the perspective of walking hydraulic system. In this paper, the anti-skid hydraulic system with large and small damping switching, the anti-skid hydraulic system with double closed walking pump, and the active floating anti-skid hydraulic system are designed respectively. The correct and reasonable design of anti-skid hydraulic system is of great significance to the safety and stability of aerial work platform.

With certain pressure resistance and sealing properties, the aviation fitting, a basic pipeline connector, is widely used in aircraft hydraulic, fuel and environmental control systems. Meanwhile, it often arises quality problems such as “dropping, bubbling, dripping and leaking” in the process of aircraft application and has an important impact on aircraft reliability and safety. Aviation fittings can be divided into permanent fittings and detachable fittings, among which permanent fittings are a type of permanently connected, non-removable fittings with not only small weight and volume, but also high endurance and reliability, which are widely used in civil aircraft. This paper introduces a foreign advanced permanent externally swaged fitting, performs structural design and prototype fabrication, simulates and analyzes its crimping process and sealing principle by ABAQUS, and conducts static and dynamic performance tests to verify the performance in accordance with AS4459B.

In view of the low reliability level of hydraulic cylinder for construction machinery in our country, the research and application of hydraulic cylinder reliability test method and device in the industry has just started, and the problems such as lack of professional personnel and industry standards, etc.. The reliability test method of hydraulic cylinder for construction machinery and the technical development and research results of the test device are introduced. It is hoped that the method of reliability test can provide reference and inspiration to the technical personnel in the process of product development and product improvement, and promote the technical progress of the industry.

In this paper, the industrial status of low-speed and high torque hydraulic motor in China and overseas is analyzed. Then their technical gaps in the important performance indicators such as the maximum working pressure, the maximum output torque, the range of rotation speed, service life, etc are clarified. Based on the classification of the current effective national and industrial standards for low-speed and high torque hydraulic motor, the basic indicators, core indicators and progressiveness indicators of motors are put forward. Besides, the technical differences in the test methods of core indicators in the standards of machinery industry and shipbuilding industry are compared and analyzed. The problems existing in the scope, test methods and technical indicators of current industry standards are pointed out, and the suggestions on standardization are put forward, so as to provide an reference for the subsequent draft and revision of industry standards.

Hoping to deepen the understanding of the hydraulic system elasticity. This paper will start with an example to analyze the difference and reason and solution between expectation and design. By a logical extension of this point, which working conditions of hydraulic system elasticity can not to be considered in design, and which working conditions must be paid enough attention to the overall elasticity, and needed theoretical calculation, which first decompose the hydraulic system elasticity, and then calculate each component, and finally summary.

In order to solve the pressure loss problem of LS feedback loop of multi-way valve, a set of pilot proportional pressure valve, hereinafter referred to as pressure valve, is designed. When the input pressure changes, the proportional electromagnet is controlled to determine its pressure output, so that the output pressure is equal to the maximum working pressure of the multi-way valve. This paper introduces the principle and structure of the pressure valve, builds a simulation model of the pressure valve with AMESim software, sets the parameters of the model, simulates the static and dynamic characteristics of the pressure valve, and discusses the key factors affecting the characteristics of the pressure valve, which provides a theoretical basis for the design and control of the pressure valve. The test results show that the error between the output pressure of the designed pressure valve and the maximum working pressure of the multi-way valve is less than 0.23 MPa.

Roadheader is often used in tunnel construction, and it is developing towards the direction of large-scale. The power demand is increasing, which puts forward the demand of high pressure and large displacement for the core component pump of the drive system. The service life and reliability of the pump are directly related to the technical level of the roadheader. Based on this, this paper proposes a life prediction method for a domestic axial piston pump, establishes an accelerated life model, extracts key characteristic parameters through accelerated test, obtains the accelerated life of the pump, and calculates the life of the pump under rated working conditions. Through the actual loading application of the pump in the roadheader, the accuracy of the life prediction is verified, and complete the reliability evaluation of the confidence interval based on the predicted lifespan of the pump.

The filter plays an important role in ensuring the normal operation of the hydraulic system. In order to improve the performance of the hydraulic system, higher requirements been given to the filter. In order to clarify the distribution of contaminated particles in the filter, a computational fluid dynamics model of a certain type of filter was established. The viscous resistance coefficient and inertial resistance coefficient of the porous medium model was obtained by fitting the experimental results of the relationship between the pressure difference and flow of the filter. After setting the parameters of porous media boundary conditions, the distribution of contaminated particles at the upstream and downstream of the filter screen was simulated from the two aspects of velocity inlet and pressure inlet. It was found that the particle accumulation density in the fluid domain of the upper shell of the filter was large. Particles larger than the diameter of the filter screen are mainly distributed at the lower end of the four inlets of the upper end cover and around the lower half of the filter screen. small-sized contaminated particles enter the skeleton through the filter screen, and the distribution density of the upper part is high, and the lower part is low. The research provides a reference for the filter design.

A type of high pressure solenoid value external seal using gas acid rubber O ring and retaining ring combination of sealing structure in the case of high temperature and normal temperature sealing, low temperature is affected by parts shrinkage and other conditions, prone to leakage at low temperature -50 ℃ serious. This paper mainly studies the problem, analyzes the root cause of low-temperature leakage, and carries out the cooresponding optimization and test verification, which effectively solves the problem and improves the reliability of the product.

At present, hydraulic cylinder is widely used in construction machinery, agricultural machinery, sanitation machinery, mining machinery and so on. Different uses, the external connection structure of the hydraulic cylinder also has a great difference. With the diversification and complexity of the use and function of the hydraulic cylinder, the external connection structure of the hydraulic cylinder also tends to be diversified and complicated. These diverse and complex joint structures are usually achieved by welding. How to ensure the external structure of the hydraulic cylinder welding, position size and shape size, it needs to be considered in the production practice. This paper mainly introduces several typical applications of hydraulic cylinders, and illustrates how to ensure the welding size of the external parts of the cylinder of hydraulic cylinders. Give you in the actual work in the encounter of similar problems to provide some ideas for your reference.

Aiming at the abnormal high frequency pressure pulsation components in the NVH test of new hydraulic pump products, the causes of the problems are analyzed by the pressure pulsation theory of hydraulic pump and the simulation model of the pump test bench. Using AMESim batch analysis tool, the influence of the slender pipe parameters of the pressure measuring port was analyzed, and the test scheme was optimized. It was found that the high-frequency pulsation component was 3 to 4 orders higher than the basic spectrum component of the pump port. The new scheme eliminates the interference of pressure measuring pipeline, and the test results are more in line with the theoretical model. The influence of pressure measuring pipeline parameters analyzed can also help to improve the NVH characteristics of subsequent products.

In order to study the fast response characteristics of axial piston pump, the mathematical model of swashplate variable of hydraulic variable pump was established. Through the control of the main parameters such as moment of inertia, pressure and area, the axial piston hydraulic pump was tested and verified. The test data curve obtained from the test verified the accuracy of the mathematical model. And reflects the moment of inertia of inclined plate component, variable piston chamber pressure and its area of influence on hydraulic variable pump fast response characteristics, the results show that the smaller the moment of inertia of inclined plate component, variable piston chamber pressure is higher, variable piston cavity area, the greater the rapid response of the axial piston pump faster, but the greater the variable piston chamber area, variable process requires the hydraulic oil flow rate, the greater the If the oil supply is insufficient, the pressure of the variable piston chamber will fall, affecting the rapid response of the variable pump.

The internal flow field temperature of double circular arc helical gear pump increases obviously at high speed, which has adverse effect on the performance of gear pump. In order to explore the influence of temperature on the performance of gear pump, the mathematical model of volume efficiency and temperature of double arc helical gear pump is established. Using dynamic mesh technology, different inlet temperatures are set by PumpLinx to simulate the changes of internal flow field of gear pump under different working conditions. The results show that the temperature of the inlet oil is different, and the temperature of the internal flow field changes obviously. The higher the inlet temperature, the more obvious the temperature rise. The serious temperature rise area is the pressure difference area, and the greater the pressure difference, the more obvious the temperature rise; with the increase of temperature, the cavitation of internal flow field is obviously weakened. Compared with the case of normal temperature oil, when the inlet oil temperature is 60 ℃, the flow pulsation and flow pulsation rate of the gear pump increase obviously, the outlet pulsation rate of the pump increases by 4.74%, the average flow rate of the pump outlet decreases by 1.52 L/min, and the volumetric efficiency of the pump decreases by 3.04%. The increase of temperature has an adverse effect on the performance of the gear pump, which verifies the correctness of the mathematical model of temperature and volumetric efficiency.

A detailed model for a rotationally balanced constant-pressure dual-row axial piston pump was meticulously developed, followed by an extensive AMESim simulation. This simulation investigated how outlet pressure impacts flow, the correlation between outlet pressure and the distribution plate's rotation angle, and the pump's dynamic behavior with sudden changes in the variable orifice signal. The analysis considered the nuanced effects of reset spring stiffness in the variable mechanism and valve stiffness in the pressure control valve. The findings highlighted a decrease in outlet flow with rising outlet pressure and an increased rotation angle of the distribution plate. A stiffer reset spring led to quicker dynamic response and reduced overshoot in the pump. Conversely, a larger valve core diameter slowed down the pump's dynamic response, prolonged steady-state attainment, and intensified flow and pressure oscillations by amplifying the distribution plate's rotation during that phase.

ABS braking system is an important part to ensure the safety performance of the car, and a comparative study of automotives ABS control strategies is conducted for the problems of nonlinearity and time-variability of the braking system in the braking process. The linear braking process is studied and analyzed, and an anti-lock hydraulic system with a single wheel is established based on AMESim, and the single-wheel dynamics model is established used Simulink, and a fuzzy PID control strategy with slip rate error and change rate as input and a self-seeking optimal control strategy with brake torque change rate as input are used. The two control strategies are simulated for ABS braking on a single dry road, wet road and 1.5 s after braking when the wet road changes abruptly to dry road for multiple road conditions at a vehicle speed of 90 km/h, and the braking results are compared. The results show that the fuzzy PID and self-seeking control methods can prevent wheel locking in the braking process, and the self-seeking control method not only has shorter braking time, but also can better cope with the sudden change of road conditions, which verifies that the self-seeking control has stronger robustness and better braking effect.

In order to solve the problem that it is difficult to directly and accurately measure the motion characteristics of high-speed moving components, such as pilot operated high-pressure pneumatic solenoid valve, whose valve core has small motion displacement and whose structure is enclosed in the valve body, a measurement method of opening characteristics based on high-speed camera small displacement amplification mechanism is proposed. The resolution analysis model was established, the test system was built, and the opening characteristics of the two position two way high-pressure solenoid valve with a diameter of 20 mm were tested under various pressures. The change rule of the opening characteristics of the pilot type high-pressure solenoid valve with the working pressure was obtained, which verified the feasibility and accuracy of the method, and provided a reliable method for the measurement of the movement characteristics of the high-pressure small displacement valve core.

For the X-ring in the piston of the servo hydraulic cylinder, the executive element in the servo hydraulic system, the finite element analysis software ANSYS was used to establish its two-dimensional axisymmetric finite element model to study the influence of the X-ring seal on the Von Mises stress and the maximum contact pressure of the main contact surface under the conditions of different parameters of groove arc radius, fluid pressure and initial compression ratio. The results show that the sealing performance is best when the groove arc radius is 2.6 mm during the internal stroke, and the best sealing performance when the groove arc radius is 2.2 mm when the outer stroke, and the sealing performance of the X-shaped sealing ring gradually deteriorates in the range of fluid pressure of 10~20 MPa. When the initial compression ratio is 5%~15%, the sealing performance gradually becomes better.

Considering that the current research of hydraulic cylinder piston rod seal is mainly to analyze the sealing performance of single seal in the initial stage, while enterprises mainly adopt series sealing structure to enhance the sealing performance in manufacturing. Considering the factors such as seal material degradation, working condition and tight gap, finite element software is used to analyze and compare the contact stress and compressive stress change over time of tandem seal structure and single seal. The seal stress variation is combined with the reliability model to analyze and calculate the time-varying reliability of the tandem seal structure. The simulation and calculation results show that the reliability of the tandem seal is better than that of the single seal. In the case where the seal gap pressure is not greater than the working oil pressure, the inter-seal pressure variation has no significant effect on the reliability of the tandem seal.

A type guiding pilot solenoid valve in the deputy value machining is completed, according to the processing technology for surface plating kam treatment, after complete the table, found the whole batch of vice valve plastic seal face bulging metal substrate surface, if the state deputy value in electromagnetic value, in many times after plastic sealing piece is loose, the emergence of the risk, lead to smaller vice valve seal failure, so that the solenoid valve Air leakage. In this paper, the causes of this problem are analyzed, and the corresponding structure and process optimization of the auxiliary valve is carried out, which effectively solves this problem, and improves the product reliability and processing quality.

The boom type concrete pump truck can continuously deliver concrete to the pouring site through the spreader bar, thus increasing the efficiency. As the executive component of the boom mechanism, the boom hydraulic cylinder bears the load and hydraulic impact brought by the boom. The particularity of the pump truck boom distribution puts forward very high requirements for the safety and reliability of the hydraulic cylinder. Combined with the actual fault feedback case of the product, this paper introduces the common fault modes and solutions of the boom cylinder of the pump truck in detail. The corresponding improvement measures have all been applied in the products and achieved good results.

Under the dual action of nitrogen pressure and its own gravity, the pneumatic hydraulic piling hammer drops at an acceleration that exceeds the acceleration of gravity, which can achieve greater strike energy in a shorter stroke. The substitute drilling member is located between the hammer core and the pile body, which plays the function of transmitting the impact energy to the pile body, and is an important part of the entire hydraulic pile hammer.Based on the finite element analysis method, the strength and stiffness analysis of the new substitute structure was analyzed by ANSYS software, and the results showed that the maximum stress was 292 MPa, while the yield strength of the material was 785 MPa, the safety margin was sufficient, and the maximum deformation was 1.84 mm, which met the working conditions of 3500 kJ of impact energy. Using the limit strength, the S-N curve of the material is estimated by the power function equation, and the fatigue life analysis is carried out on the substitute based on the linear fatigue cumulative damage theory, and the analysis results show that the minimum life is 4.77e+6 times, which meets the requirements of 1 million times of use.The analytical methods and research results presented in this article can be used as a reference for the design and analysis of pneumatic hydraulic hammers.

To improve the internal leakage of the balance valve used in the telescopic system of the truck crane, this paper analyzes the structure of the balance valve, and obtains the parts and process parameters directly related to the sealing performance of the balance valve; Verify the reliability of the measurement system through the measurement system analysis (MSA); Through process capability analysis, the process parameters of insufficient processing capability are obtained, and the cause of internal leakage of balance valve is determined; Combined with the production process of balance valve, 32 possible factors were screened by using the C&E matrix and the potential failure mode and effect analysis (FMEA), of which 19 factors could be improved immediately, and the effect after improvement was significant, and the balance valve manufacturing process was significantly improved; Use hypothesis test to verify the correlation between the remaining 13 factors and process parameters, and further screen out 8 relevant factors; Finally, eight factors were tested to obtain the optimal feed rate, optimal speed and processing law. When added to the production and processing process, the feedback rate of internal leakage failure decreased from 4.72% to 2.35%, effectively improving the internal leakage of balance valve.

There are many reasons for the wear of the sealing ring of the hydraulic cylinder. It is difficult to observe directly through the naked eye, and it is difficult to find the direct cause. The wear analysis method of hydraulic cylinder seal ring based on finite element method is proposed. Based on the geometric model, material model and physical model of the hydraulic cylinder seal ring, the nonlinearity of the rubber seal ring in stress and strain is analyzed, and the finite element model of the hydraulic cylinder seal ring is constructed by defining the strain density function. According to the sealing structure of the hydraulic cylinder piston, the movement characteristics of the hydraulic cylinder piston are analyzed, and the appearance feature changes of the seal ring are described by using the Archard model. The wear depth of the seal ring at any point on the contact surface of the seal ring is calculated, and the wear amount of the hydraulic cylinder seal ring is analyzed. The test results show that the research method can effectively analyze the crack depth and crack propagation angle of the hydraulic cylinder sealing ring. The test analysis results of the two indicators are basically consistent with the measured results. The maximum error of the test analysis of the crack depth is only 0.002 mm. Therefore, it shows that the research method is helpful to improve the sealing reliability of hydraulic cylinder design.

Packer is an important part of oil production equipment, and its excellent performance will directly affect the production. Conventional packers are mechanically set and unsealed by the self-resilience of the rubber cartridge. However, in extreme cases, it is easy to cause compression failure of packer rubber cylinder due to excessive setting force, and the rubber cylinder is damaged and unable to bounce back during unsealing. Therefore, a micro-hydraulic system is designed in this paper, which can realize the coordinated control and accurate adjustment of the pressing force and unpacking force of the hydraulic packer, so as to ensure the safety and reliability of the actual work of the packer. The AMESim system simulation model is built to simulate the setting and unsealing process in the process of motion, and the influence of factors such as the flow resistance at the oil suction, the load at the outlet, the speed of the piston pump and the closed volume in the sliding cylinder on the dynamic characteristics of the hydraulic system is studied. Finally, the parameters of the hydraulic system are optimized. The results show that the response rate of the whole system can be improved by adopting the measures of pressurizing the inlet of the micro-hydraulic system, increasing the rotational speed and reducing the flow resistance at the suction point.

Aiming at the traditional hydraulic propulsion system, this paper designs a two-stage hydraulic propulsion device which takes the external seawater as the working medium, accumulator as the power source and new two-stage synchronous seawater hydraulic cylinder as the core component. This paper discusses the structure of a new two-stage synchronous seawater hydraulic cylinder and the working principle of seawater hydraulic propulsion device, and establishes the simulation model of the propulsion system by AMESim. The experimental verification is carried out through the built test bed. The results show that the accumulator charging process is negatively correlated with the accumulator initial pressure in the energy supply process. In the process of propulsion, the velocity of the object leaving the propulsion pipe is positively and linearly related to the root of the accumulator initial pressure.

This article presents the development of a performance testing system for metallurgical rolling servo hydraulic cylinders, which uses a combination of LabVIEW and MATLAB functions. The testing system includes functional modules for evaluating the dynamic and static performance requirements of the cylinders, such as testing the minimum starting pressure, loaded dynamic friction force, step response, frequency response, and swing testing. To collect the test results, the system uses Advantech data acquisition cards, including PCI-1742U, PCI-1723, and SSI-RS485 current transmitters, to gather signals from MST displacement sensors and AB phase pulse sensors. The system is capable of real-time tracking, display, storage, and query of test data, as well as data export and report printing. Experimental results demonstrate that the system exhibits high real-time performance and operability, and fills the gap left by other systems in terms of swing testing for large-diameter metallurgical rolling servo hydraulic cylinders. Additionally, the testing system offers greater stability and solves the problem of complex operation for technical personnel who used the previous testing system. The system achieves “foolproof” operation and greater intelligence, visualization, and timeliness.

As a safety valve for axial piston variable displacement pumps or axial piston variable displacement motors, the performance of the pilot operated high-pressure relief valve will directly affect the safety and reliability of the axial piston variable displacement pump, axial piston variable displacement motor, and system. This paper introduces the working principle and mathematical calculations of a certain type of high-pressure relief valve in our company, and establishes a simulation model using AMESim to explore the effects of the pre tightening force of the pilot spring and the main valve spring on the opening pressure, pressure overshoot, pressure overshoot stabilization time, and unloading time of the high-relief valve. This has guiding significance for the design of high-pressure relief valve.

Aiming at the internal diameter roll forming process of non-flared conduit joints, the three-dimensional rolling process is simplified to a two-dimensional plane for analysis, and the forming torque equivalent conversion equation is established. Based on ABAQUS to establish a two-dimensional finite element model of flareless conduit joints, simulation and analysis of the roll forming process, to get the rolling process of torque phase change trends and regional characteristics of conduit deformation force. The connection strength test is carried out on the joint body, and the difference between the simulation and the test is 5.8%, which verifies the accuracy of the simulation model. To explore the effect of forming torque on the performance of joint body, a multi-group molding torque is selected for simulation analysis, and the molding performance of the joint body is evaluated by combining the residual stress, deformation distribution, filling state and connection strength of the conduit. The results show that the molding torque range is 0.68～1.13 N·m, and the filling rate of the rightmost groove of the sleeve is 100% when the torque is 1.04 N·m, which is the optimal molding performance of the joint body.

In view of the sudden increase of return oil pressure in the accelerated life test of hydraulic piston pump, the preliminary judgment, decomposition inspection, differential measurement and physical and chemical analysis of the fault phenomenon are completed. Through the re measurement of the crown value of bearing roller over the years, it is found that the unreasonable design value of roller crown is the main cause of product failure. Through statistical analysis and test verification, The reasonable crown value of bearing roller is determined.

Electro-hydraulic actuators are widely used in industrial devices for their advantages of fast response, high accuracy, and large driving force, which are used to transfer power and motion. The realization of the function of the electro-hydraulic actuator depends on a reliable control system. Aiming at the opening and closing of special valves in the chemical plant, a closed loop position control system based on PLC technology is designed. Through the digital PID control algorithm, the dynamic control of material flow and pressure balance of valves in the refining and chemical plant is realized.

In this paper, the jitter problem caused by spool movement of crane winch balance valve in the process of opening and closing is studied. Based on AMESim simulation software, the simulation model of crane winch balance valve is established. Through simulation analysis, the dynamic characteristics of spool movement of the balance valve are deeply studied. The internal damping hole parameter design of crane balance valve has great influence on the reset action of the valve spool. Optimization of damping hole parameters can effectively solve the problem of crane winch falling jitter.

This paper establishes a thermo-hydraulic-solid multi-field coupling simulation model of the axial piston pump by considering the coupling deformation of the cylinder and the distributor of the distributor friction pair. The results can visualize the different temperature and deformation dynamic distribution processes of the two mating surfaces during the motion of the whole pump, thus revealing the influence law of multiple factors on their surface oil lubrication characteristics and pointing out the weights of the influence of each factor. The results show that: the pressure and temperature of the mating sub-fluid and the thermoelastic deformation of the two surfaces of the mating sub-fluid have a coupling interaction effect, in the high-pressure pressure area of the mating sub-fluid of the axial piston pump, due to the higher pressure, the structural deformation and temperature distribution in this area is larger. The increase of pressure and speed under different working conditions leads to a positive comparison of the stress-deformation and temperature distribution of the structure. The weight of pressure on both deformation and temperature is greater than 60%, which is significantly greater than the effect of speed, for which pressure plays a decisive role.

The solenoid valve realizes the electronic control release function of high-pressure oxygen for the oxygen system of a certain type of rocket engine, and outputs the high-pressure oxygen electronically controlled by the cylinder for the back-end engine to use the gas of the required pressure to provide oxygen for the engine.The response characteristics of the solenoid valve have a decisive influence on how fast the system reacts.From three aspects: theoretical analysis, experimental research and numerical simulation, the dynamic response characteristics of the solenoid valve under no-load and load are compared and analyzed, and the results show that:The maximum error of the opening time and release time calculated by the three methods is not more than 10%, which verifies the accuracy of the finite element model in predicting the response characteristics of the solenoid valve, and provides an effective method for the design and matching of its parameters.

In order to study the influence of the changing law of the impeller passage area on the hydraulic performance of a nuclear main pump, based on the global structured grid, using SST k-ω turbulence model, steady numerical calculation were carried out for 5 groups of model pumps with different passage area changing law. For the optimum hydraulic performance, the changing law of the passage area along the flow direction are studied and analyzed, and the performance test is carried out to verify the optimal scheme.The results show that the calculated efficiency of the optimal pump scheme is only 0.22% higher than the test value, indicating that the prediction accuracy of the efficiency is high. The pressure field in the impeller changes with the change of the distribution law of the passage area, but the velocity profile is always highly similar, and the main factor affecting the impeller hydraulic efficiency is the distribution characteristics of the pressure field. On the premise that the inlet and outlet areas of the passage remain unchanged, the impeller hydraulic efficiency is the highest when the increase rate of the passage area along the flow direction shows a trend of first fast and then slow, 0.81 percentage points higher than the hydraulic efficiency of the first slow and then fast change trend. The optimization measures of having a large area gradient at the passage inlet and making the area gradient decrease rapidly along the flow direction are conducive to improving the hydraulic efficiency of the impeller.