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.

Aiming at the high performance design of end face structure for spiral groove mechanical seals with liquid film lubrication, the entropy production loss method was adopted to carry out the numerical calculation of the three-dimensional turbulence flow field and groove optimization design of spiral groove mechanical seal; The pressure distribution of flow fields with different grooves were analyzed; The leakage rate, opening force and entropy production loss of the seal at different speed and groove depth conditions were calculated. The results show that the optimal spiral angle, groove-ridge ratio, groove-dam ratio and groove depth is 20°, 0.42, 0.63 and 13 μm, respectively; the optimal seal end face dynamic pressure opening ability is large, and the flow entropy production loss is small; The leakage rate and opening force increase linearly with the rotational speed and groove depth, the entropy production loss increases parabolically with the rotational speed and vary little with groove depth. The multi-objective optimization design method constructed can provide design guidance for low leakage, and low-energy mechanical seal structures.

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.

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.

The hydraulic servo electro-hydraulic actuator integrates the control module and the hydraulic power module, the control module issues instructions to the intelligent controllable servo valve, the control hydraulic power module outputs force (or torque) with linear displacement (or angular displacement), drives the controlled object and completes the adjustment process through displacement feedback and pressure feedback to achieve closed-loop control of various functions. The built-in Internet of Things communication module can remotely monitor the operating status and fault diagnosis of the valve and cylinder. Using high-performance microprocessing controller, it can communicate with a variety of fieldbus sensors, such as SSI, 5V differential pressure orthogonal TTL encoder, Profuse-DP bus and other digital sensor interfaces, and can realize a variety of fieldbus control. It can realize position control, real-time position speed control, pressure (force) control, position-pressure (force) compound control, speed-pressure (force) compound control, multi-axis synchronous control and coordinated control, multi-axis controller combination as the slave axis and the main controller communication, up to 64 axis synchronous control or 32 axis coordinated control.

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 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.

In the high pressure condition, the increase of internal clearance of gear pump will aggravate the leakage inside the pump and seriously affect its volumetric efficiency. Axial clearance and radial clearance are the two main ways of internal leakage of the pump, and the mathematical model of liquid leakage and clearance value in the two kinds of clearance is analyzed. The main influencing factors of axial clearance include: gear shaft deflection deformation, gear shaft eccentricity and pump body wear and structural deformation; while radial clearance is mainly affected by gear pump end cover deformation and multi-physical field coupling, and the research conducted at home and abroad for these five aspects is reviewed. In order to control the amount of internal clearance leakage in the pump, the research content of optimizing and controlling the internal clearance is reviewed. Finally, it is pointed out that understanding the local size variation of the gear pump clearance is an important reference for studying the flow characteristics and internal structure design of the pump.

The wave compensation system of offshore trestle can realize the safe and efficient transfer of personnel and materials at sea, and is the key system of large marine operation and maintenance ships. Aiming at the bottleneck problem of high energy consumption in the wave compensation system of offshore trestle, a design scheme of active- passive composite wave compensation electro-hydraulic system for pitching joint of offshore trestle is proposed in this paper. Firstly, this paper analyzes the mechanical structure of the wave compensation system and its working principle of the pitching joint. A passive wave compensation system based on high-pressure gas follow-up support is designed to reduce the energy consumption caused by gravity during the pitching action of offshore trestle. An active wave compensation hydraulic control system based on electro-hydraulic valve group is designed to realize the closed-loop control of pitching motion of offshore trestle. Then, through theoretical modeling and simulation analysis, the mechanism of the designed system to compensate the trestle's dead load is revealed, the energy distribution of the passive compensation system and the active compensation system is analyzed, and the energy consumption characteristics of the designed active-passive composite wave compensation electro-hydraulic system under different passive compensation pressures are explored. Finally, the active-passive composite wave compensation electro-hydraulic system for pitching joint of offshore trestle is developed, and the driving and control capability of the designed system is verified by experiments. The results show that the designed active-passive composite wave compensation electro-hydraulic system can realize the low energy consumption and high precision control of the offshore trestle, which has important strategic significance for the future installation, operation and maintenance of offshore wind power in China.

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.

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 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.

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.

Electro-hydraulic servo valve is the core control element in high-precision deep-sea hydraulic equipment, and its performance and reliability are the key factors to determine the control accuracy and reliability of deep-sea hydraulic system. Under the extreme working conditions of the deep sea, the tiny deformation of the valve spool and the valve sleeve affects the control performance of the electro-hydraulic servo valve. This paper establishes a three-dimensional model of the double-nozzle baffle valve, and based on the environmental conditions of the variable depth of the sea, it studies and analyzes the deformation law and internal leakage of the slide valve under different depths of the sea. The results show that when the sea depth is 12 000 m, the gap between the spool and the valve sleeve is reduced to 2.752 μm, and the leakage is reduced to 0.020 5 L/min, which is close to 50% of the deformation and 98% of the leakage compared with the land environment. The results can be used to predict the use of electro-hydraulic servo valves in deep-sea environments, and this study is of great significance to the research of hydraulic systems.

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.

In view of the complex stress condition of the internal gear pump crescent plate, which is prone to breakage, and is a key component that is prone to damage and failure in the high-pressure internal gear pump, the force analysis of the combined crescent plate is carried out. Through Solidworks software modeling, using Pumpinx software to analyze the flow field, the force of the crescent plate under the stable working state of the internal meshing pump is obtained, and it is concluded that the larger the gear meshing center distance, the smaller the pressure fluctuation on the surface of the crescent plate; the first clearance The greater the inlet angle of the flow field, the greater the force on the easy-bending surface of the gap; the greater the inlet lift, the greater the force; when the flow field structure of the first gap is changed to a U-shaped structure, the force on the easy-bending surface of the gap decreases. 4.9%, which can effectively improve the service life of the pump, and provide a reference for the design and research of the crescent plate of the high-pressure internal gear pump.

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.

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.

In order to solve the problem that the hydraulic cylinder retracting speed is too fast when the fork of electric forklift truck is carrying the weight, which is prone to damage the cylinder block and pipeline and the fork holding weight is different, the hydraulic cylinder extending speed is not controllable, the hydraulic lifting system of electric forklift truck is optimized, and simulation verification is carried out. The hydraulic lifting system is designed according to the design manual. The working pressure of the primary system is 16MPa. The accumulator is parallel to absorb the flow pulsation on the outlet circuit of the hydraulic pump. The speed regulating valve is configured on the rodless chamber inlet circuit of the hydraulic cylinder to realize the pressure compensation for different weights and make the lifting speed controllable. The hydraulic cylinder piston rod provides back pressure when the load is retracted to avoid the piston rod free fall damage to the hydraulic cylinder; The hydraulic components are designed and selected. Choose CBG2100-BF100 hydraulic pump and HSGL-100/70E-231-3000×3280 hydraulic cylinder, 3WE10E31B/CG24N9Z4 electromagnetic reversing valve and RVP30-10B check valve, DBDS30P10B sequence valve, THF-G10 speed regulating valve ; The hydraulic system is studied by the principle of power key and graph, and the dynamic characteristics of the hydraulic system are studied by digital simulation. The mathematical model of the hydraulic system is built by the simulation software AMESim, and the parameters of key components are simulated. The simulation results show that it takes 8 s for the cylinder piston rod of the optimized hydraulic system to fully retract without oscillation, and the operation is stable. The oil port flow rate of the cylinder piston rod is 87 L/min when the cylinder piston rod is retracted, and the flow pulsation generated by the hydraulic pump is absorbed by the accumulator. The system runs stably and meets the design requirements, and the hydraulic lifting system is theoretically feasible and reliable.

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.

Many vocational colleges currently offer practical training courses related to hydraulic and pneumatic technology, but due to space limitations or insufficient equipment, it is difficult to apply the complex hydraulic and pneumatic comprehensive training platform to the actual teaching process. In response to the appeal issue, this article designs a comprehensive teaching equipment for mechanical arms based on digital twin technology for the “Hydraulic Transmission and Pneumatic” course experiment, and conducts research on the teaching content of hydraulic and pneumatic technology training courses based on this set of training equipment. The content involves the recognition of basic knowledge of hydraulic and pneumatic, the assembly of mechanical arms, the connection of pneumatic (hydraulic) circuits, the design of control systems, and the digital twin debugging of the entire machine. Each teaching unit is divided into virtual debugging and physical operation parts. After students independently complete equipment cognition and system simulation debugging in the virtual equipment, they are divided into groups and batches for practical practice and functional verification of the physical devices. Through this virtual real teaching mode, the demand for physical equipment in the teaching process is reduced, and students have more practice opportunities in the practical training learning process, which can provide students with more practice opportunities during the practical training process, so as to improve the teaching quality of hydraulic and pneumatic technology training courses.

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.

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.

Particle erosion wear phenomenon occurs on the blade surface when wind turbines operate in sandy and dusty weather, leading to changes in blade morphology and degradation of its aerodynamic performance. In this paper, the dynamic erosion prediction method based on the coupled flow-solid-erosion model is used to simulate the erosion process of the NREL S809 straight wing section, to study the dynamic evolution of the surface wear caused by the particle erosion of the S809 straight wing section, and to analyze the change of the surface morphology of the S809 straight wing section and its impact on the aerodynamic performance under the conditions of different particle sizes. The study shows that: with the advancement of the erosion time, the cumulative effect of the erosion wear on the leading edge of the S809 straight wing segment surface is obvious, and the wear caused by the particles on the surface of the wing segment is intensified, and the depth of the erosion crater is gradually increased, which results in the fluctuation of the pressure coefficient of the surface of the airfoil and the increase of the degree of the static pressure disorder. With the gradual change of leading edge wear morphology, the turning position of the suction surface of the airfoil is gradually disorganized.

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.

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.

Involute gear pumps and piston pumps have limited application scopes due to their respective structural. To address this issue, a self-pressurizing pump with a pressure rating between gear pumps and piston pumps is desgined. This hydraulic pump effectively harnesses the effect of squeezing and increasing the oil pressure as the variable volume camber formed during the meshing of involute gears contract. Additionally, oil suction and discharge are accomplished via the flow distribution windows. Based on analysis of its working principle, a corresponding three-dimensional fluid models is developed. Numerical simulation of the pumps‘s flow characteristics, pressure characteristics, radial unbalanced force, and cavitation characteristics are conducted using Pumplinx. The simulation results reveal: Firstly, each rotation of one tooth of the self-pressurizing pump, both the pressure and flow display two minor fluctuations. Secondly, the radial unbalanced force is more pronounced compare to that of traditional gear pumps. Thirdly, cavitation is notably evident at the inlet and in areas where the variable volume camber formed by gear meshing expand. Finally, a substantial increase in the output pressure can be achieved through two-stage continuous pressurization. These results confirm the feasibility of the self-pressurizing pump principle, providing a theoretical and design foundation for desgin.

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.

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.

The seawater environment is harsh and complex, and the metal parts of conventional mechanical seals will be severely corroded in the seawater environment. The friction pairs are prone to failure and leakage under the wear of hard impurities in seawater, greatly reducing the service life of mechanical seals. To ensure the safety and stable operation of underwater equipment, a mechanical seal is designed for underwater use. The metal components are made of duplex stainless steel material, which has good corrosion resistance. The friction pair adopts a “hard and hard” structural form, which can resist the wear of seawater impurities. In addition, the non compensating ring end face is treated with a hard coating, which improves surface hardness and reduces surface friction coefficient. The seal was subjected to a continuous 5 h running simulation test, using oil as the process medium, and the leakage amount reached 0.33 mL/h under the working condition of pressure of 0.1 MPa.

In centrifugal pumps and other rotating machinery, the mouth ring is usually used as a part to reduce the leakage flow, but with the decrease of the mouth ring clearance and the increase of the rotor speed, the influence of the rotor dynamic characteristics on the safe operation of high-speed pumps cannot be ignored. Based on the numerical simulation method, the stiffness damping characteristics of the mouth ring of a high speed centrifugal pump under working condition are calculated and studied in this paper. By modeling the flow field of a high speed centrifugal pump, the stiffness damping characteristics of the rotor in the mouth ring with different eccentricities and deviation angles are calculated. The results show that the stiffness damping characteristics of the mouth ring clearance are nonlinear related to the rotor eccentricity. The influence of inlet pressure distribution on stiffness damping of rotor under different eccentricity and deviation Angle is obvious. The circumferential asymmetry of inlet pressure causes the circumferential asymmetry of stiffness damping characteristics of mouth ring, in which the influence of main stiffness is most obvious.

Focus on hydraulic pressure fluctuations in traditional accumulators during energy storage and release, a spring-based constant pressure accumulator is proposed. The operational principle of the accumulator is analyzed, with the profile curve equation for the critical component derived and solved. Key parameters for an accumulator in a specific hydraulic system are designed. A simulation model is constructed in ADAMS software to test the performance of the accumulator under varying flow conditions. It achieved a force deviation below 1% during stable operation, serving as a reference for the design of hydraulic energy storage systems.

Ball screw is a key transmission component in electro-hydraulic servo equipment, and its structural design will have a direct impact on the mechanical properties and further affect the stability and life of its transmission. The system was analyzed by ABAQUS solver to study the ball load carrying situation and the influence of nut structure on its load. The results show that the secondary development of ABAQUS based on Python can realize the whole process of finite element parametric modeling and static analysis of ballscrew sub-systems, which provides data and methods for the subsequent study of the optimization of the structural design of the nut returner and the selection of materials.

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.

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.

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.

Introduce a rescue boat davit that meets the requirements of the International Convention for Safety of Life at Sea (SOLAS), provide a detailed description of the basic structure and working principle of the rescue boat davit, and provide a calculation method for hydraulic system design and main component selection for reference.

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.