Hydraulic Buffer Research Articles

Experimental and simulated studies on hydraulic buffering valve for ZF-4WG308 power-shift transmission

The structure and working principle of a hydraulic buffering valve for a power-shift transmission ZF-4WG308 were studied comprehensively, and a model of the hydraulic buffering valve was developed with AMESim. A bench test was conducted on a buffering valve for transmissions (ZF-4WG308) and the test results agree well with the simulated results. Further more, the influences of the key parameters of the valve on the buffering performance were also studied in details.

Control rod drop dynamic analysis in the TMSR – SF1 based on numerical simulation and experiment

The scram function renders the core subcritical in response to plant upsets, which is realized by fast drop of the control rods. In the solid fuel (SF) thorium molten salt reactor system (TMSR), denoted as the TMSR – SF1 project, the drop time of the rod is obviously affected by the driving mechanical drag and the hydraulic resistance of the liquid environment. An inner-house code is developed to analyze the rod drop in the TMSR – SF1. In the code, the total transmission efficiency of the driving mechanism is deduced as a relationship with dropping velocity of the rod. With the experimental and theoretic analysis, the motion process of the rod drop is simulated in this study. And it turns out that the drop time in the molten salt is satisfied with the limiting drop time in the TMSR – SF1. In addition, a hydraulic buffer is designed to alleviate the dropping shock from the scram and the calculation results are presented in the paper as well.

Study about the Effect of System Parameters on the Dynamic Properties of Hydraulic Buffer System Applied to Belt Arrestor for Downward Belt Conveyor

Background: Broken belt arrest has become a hot topic in the fields of conveyor belt protection technology in the recent years. Recent studies and patents have found that there are few researches on hydraulic buffer system applied to belt arrestor for downward belt conveyor (HBSBADBC). Keywords: Belt arrestor, buffer properties, downward belt, hydraulic buffer system, mathematic model, MATLAB/Simulink, simulation.

Hydraulic systems control based on the characteristics of major-motion mechanism for an open-die forging manipulator

In the open-die forging process, the forging manipulator must cooperate closely with the forging press. Terrible working conditions of open-die forging have resulted in significant demand on the hydraulic control systems of the forging manipulator. This article analyzes the characteristics of major-motion hydraulic systems with the aim of proposing a novel hybrid serial–parallel heavy-duty forging manipulator. Kinematic and dynamic models of the major-motion mechanism are developed to investigate the control and comply with performance of hydraulic lifting, pitching, and buffering systems. Simulation shows that the three hydraulic systems are coupled in the position and posture control of the clamp. A separate posture control method based on the characteristic of the major-motion mechanism is designed for the hydraulic systems, and the position tracking performance of the hydraulic systems is studied in a stretching process of a plat-tool.

Parameters Optimization of a Hydraulic Buffer System for Belt Arrestor in Downward Belt Conveyors

Hydraulic buffer systems play a significant role in energy absorption and improving belt arrest reliability in downward belt conveyors. In order give hydraulic buffer systems more preferable buffer properties, a parameters optimization method based on a reference model is proposed. Firstly, the working principle of a hydraulic buffer system for a belt arrestor is provided. Secondly, the mathematical model of the system is built and a reference model of buffer chamber pressure is constructed utilizing a second-order system. Furthermore, a genetic algorithm is introduced to optimize the system parameters. Finally, some simulation examples are carried out on the Simulink software. The simulation results show that the pressure peak in buffer process can drop down and that pressure fluctuation in buffer end processes decrease substantially after optimization. The parameters optimization method for hydraulic buffer systems is applicable to different structure parameters of the buffer cylinder.

유압 장치를 이용한 철도 연결기용 고용량 충격완충기의 성능시험

Coupling systems under train's collision should take the impact by absorbing the impact energy caused from the collision, so the systems are very important parts for the safety of the trains. However, it is not easy to evaluate the performance of the system because it requires a huge testing facility, which is able to control the impact and to handle many safety issues. In this paper, test results are provided, which are obtained from collision tests of a single train having a coupling system in the front, and the results are analyzed in order to understand the characteristics and the dynamic behaviors of energy absorbing materials in the coupling system, such as a hydraulic buffer, and two rubber buffers. The results show that the force of each component could be empirically described by the compression displacement and velocity. The analyzed results will be applied to simulation models, and advanced studies wouuld be available if the simulation models are well validated with the test results.

철도차량의 충돌 시뮬레이션을 위한 유압 완충기의 특성 맵

철도차량의 충돌 시뮬레이션을 위한 유압 완충기의 특성 맵

Function and structure of leaves contributing to increasing water storage with height in the tallest Cryptomeria japonica trees of Japan

In Cryptomeria japonica , transfusion tissue in leaves may have functions of water storage and supply, which could compensate for hydraulic constraints with increasing height. The tallest trees of Cryptomeria japonica occur in climatic regions similar to the world’s tallest trees. We hypothesized that tall C. japonica trees would have evolved adaptive mechanisms to overcome height growth limitation. Here, we focused on foliar water storage, a mechanism recently discovered in Sequoia sempervirens. In C. japonica, leaf water potential at turgor loss did not change with height or light availability, while leaf hydraulic capacitance and succulence (water content per leaf surface area) increased, suggesting hydraulic compensation. Plasticity of leaf morphology could contribute to avoiding negative effects of height on photosynthesis. We also focused on the structure and function of transfusion tissue in leaves and its role in water storage and supply. Cross-sectional area of transfusion tissue increased with height, whereas that of xylem was constant. We confirmed that water flowed from vascular bundle to mesophyll via the transfusion tissue. Cryo-scanning electron microscopy images of leaf cross sections showed that transfusion cells were flattened, but not fully dehydrated when leaf water potential decreased in situ and by experimental dehydration, and cell deformation was more marked for treetop leaves than for lower-crown leaves. The shape of transfusion cells recovered at predawn as well as after experimental rehydration. As in S. sempervirens, transfusion tissue of C. japonica may function as a hydraulic buffer, absorbing and releasing water according to leaf water status. Anatomical and hydraulic properties contributing to foliar water storage may be an adaptive mechanism acquired by tall Cupressaceae trees to overcome the hydraulic constraints on physiological function with increasing height.

Simple deterministic model of the hydraulic buffer effect in septic tanks

AbstractSeptic tanks are widely used in on‐site wastewater treatment systems. In addition to anaerobic pretreatment, hydraulic buffering is one of the roles attributed to septic tanks. However, there is still no tool for assessing it, especially in dynamic conditions. For gravity fed‐system, it could help both researchers and system designers. This technical note reports a simple mechanistic model based on the assumption of flow transition between the septic tank and the outflow pipe. The only parameter of this model was calibrated using computational fluid dynamics (CFD) modeling for a wide range of discharge rates. The resulting model highlights that a septic tank plays a hydraulic buffer role when faced with sudden and large discharge flow, but this role tends to disappear when input hydrographs are smoother. In those cases, there is an observable lag between the input hydrograph and outflow hydrograph.

Application of Variable Damping Hydraulic Buffer in Braking Large Mass Impact Loading Problem

Aimed at braking large mass impact loading problem, a mathematical model of the multi-orifice hydraulic buffer has been established, with the use of hydrodynamics theory, hydraulic theory and engineering structural mechanics theory. Damping characteristic curves under different operating conditions have been analyzed. The problem that traditional hydraulic buffer damping characteristics could not match to different mass impact loading well has been found. By analyzing the influence of buffer cylinder structural parameters on buffer damping characteristics, a variable damping buffer has been proposed, and the problem has been verified with simulation.

Performance Characterization and Auto-Ignition Performance of a Rapid Compression Machine

A rapid compression machine (RCM) test bench is developed in this study. The performance characterization and auto-ignition performance tests are conducted at an initial temperature of 293 K, a compression ratio of 9.5 to 16.5, a compressed temperature of 650 K to 850 K, a driving gas pressure range of 0.25 MPa to 0.7 MPa, an initial pressure of 0.04 MPa to 0.09 MPa, and a nitrogen dilution ratio of 35% to 65%. A new type of hydraulic piston is used to address the problem in which the hydraulic buffer adversely affects the rapid compression process. Auto-ignition performance tests of the RCM are then performed using a DME–O2–N2 mixture. The two-stage ignition delay and negative temperature coefficient (NTC) behavior of the mixture are observed. The effects of driving gas pressure, compression ratio, initial pressure, and nitrogen dilution ratio on the two-stage ignition delay are investigated. Results show that both the first-stage and overall ignition delays tend to increase with increasing driving gas pressure. The driving gas pressure within a certain range does not significantly influence the compressed pressure. With increasing compression ratio, the first-stage ignition delay is shortened, whereas the second-stage ignition delay is extended. With increasing initial pressure, both the first-stage and second-stage ignition delays are shortened. The second-stage ignition delay is shortened to a greater extent than that of the first-stage. With increasing nitrogen dilution ratio, the first-stage ignition delay is shortened, whereas the second-stage is extended. Thus, overall ignition delay presents different trends under various compression ratios and compressed pressure conditions.

A Summary for Mounting Buffer Technology of Overhead Weapon Stations

The article first systematically expounds the working principle and deficiencies of spring buffer, spring - hydraulic buffer, compressible liquid buffer, and other typical buffers. And then detailed introduces the generation, working principle and outstanding features of new material buffer. Finally, according to the characteristic of traditional buffer that performance parameters are immutable, presents a soft mounting buffer that performance parameters can be changed of intelligent, provides theoretic and technological reference of Overhead Weapon Stations for its development design and modification upgrade in China.

철도 차량의 연결기 시스템의 충돌시뮬레이션

In this study, a collision simulator for rolling stock that considers the plastic deformation of the car body and the dynamic characteristics of a coupler system was developed using Matlab/Simulink. Normally, a coupler system has functions for both connecting the individual car bodies and absorbing the impact energy. A coupler system is composed of a rubber buffer, hydraulic buffer, and deformation tube elements. The coupler system should protect the car body and prevent damage when the shunt speed is less than 10 km/h, which is the regulation speed based on the safety rule for rolling stock. However, if the shunt speed is greater than 10 km/h, a car body is plastically deformed. Therefore, the modeling of the plastic deformation of a car body should be included in a simulator. This collision simulator can provide the design parameters for a coupler system and car body.

CO-Simulation Analysis of Hydraulic Steel-Belt Overwind Buffer Device

In this study, we obtain overwind buffer distance by using the Lagrange equation to establish the two- degrees-of-freedom mathematical model with vertical shaft lifting system in rolling process. Design of a buffer device which is composed of a hydraulic energy absorption and strip plastic deformation energy absorbing and analyze its working principle with mechanical and hydraulic system. Analysis of the overwind buffer time and buffer distance with loaded full overwind and no-load speed by using ADAMS and AMESim to build mechanical hydraulic combined simulation model of hydraulic steel-belt overwind buffer device. The simulation results show that: buffer time is 0.67 sec and buffer distance is 0.38 m with loaded full overwind; buffer time is 0.523 sec and buffer distance is 0.05 m with no-load speed overwind. The design of Hydraulic steel-belt overwind buffer device conforms with the requirements of safety regulation in coal mine.

Mechanism Motion Analysis and Hydraulic Buffer Equipment Design Based on COSMOSMotion

Virtual simulation of the tumbling machine for huge cylindrical segment was done in the design process with COSMOSMotion module of Solidworks software. This machine could rotate from 0 to 180°. Within 0°to 53°, the rotation was driven by traction equipment. From 53°to 180°,the rotation was driven by dead-weight of the machine. Hydraulic buffer equipment and 4 rubber buffer beams were used to reduce the impact force between the tumbling table and the base. The simulation analysis shows that the structure design was reasonable and the buffer function was fine, too.

The Numerical Simulation of Three-Dimensional Dynamic-Mesh Flow Field of a Hydraulic Buffer

In order to study the dynamic changes of the internal flow field physical quantities in the hydraulic buffer of a special equipment, based on the Computational Fluid Dynamics (CFD), a three-dimensional incompressible and viscous model under unsteady condition is created. The model keeps the control rod of varying diameter and non-working chamber cover, simulates the turbulent in the flow field of the hydraulic buffer of the special equipment with dynamic meshing technology. From the results, the distributions of velocity in flow field and pressure in chamber are got. It shows that there are negative pressure areas in the non-working chamber and that will lead to cavitation. The results give us a great reference to improve the structure of hydraulic buffer.

The Simulation and Study of Buffer Device of Hydraulic Cylinder

Now, the energy buffer device which seals up part of the oil and makes it into the throttle or the gap outflow to achieve the purpose of the piston’s slowing down at the end of the stroke is widely used. At the same time, the inside pressure produced by the oil of the buffer cavity resists the inertia and other external force to achieve the buffering. The cylindrical ring gap buffer device is analyzed in detail in this paper. The model of hydraulic buffer was built based on the MATLAB/SIMULINK, the dynamic characteristics of the buffer pressure and the buffer velocity were simulated, and the influencing factor of hydraulic buffer was compared and analyzed.

Modeling and control of the pulley buffer system of arresting cable for shipboard aircraft based on magneto-rheological fluid

Taking the MK7-3 of USA hydraulic buffer arresting device as the research subject, the dynamical model for the shipboard aircraft arresting system is established, and the magneto-rheological (MR) damper is applied to pulley shock absorbers for shipboard aircraft block system. Due to the effect of the MR damper has not been known completely and so far MR damper model has not been defined, we use a set of characteristic test of the MR damper, through the process of parameters identification, to establish the dynamical model for the MR damper based on the Bingham plastic model. Then, the fuzzy control rules are designed, the buffer control for the pulley buffer of shipboard aircrafts is completed in touchdown moment based on MR technology. Compared with blocking device of hydraulic pulley buffer in the same condition, the simulations results show that the proposed MR pulley buffer can effectively recognize the impact energy for shipboard block system and reduce the pull peak of arresting cable. It improves significantly safety during landing of the air vehicles and lowers the risk of accidents.

Reciprocating Submersible Pump Improves Oil Production

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper IPTC 14966, ’Novel Reciprocating-Submersible-Pumping Technology for Performance Improvements in Oil Production,’ by Zhigang Wang, PetroChina, prepared for the 2011 International Petroleum Technology Conference, Bangkok, Thailand, rescheduled to 7-9 February 2012. The paper has not been peer reviewed. Submersible pumping by use of a linear motor is crucial for oil production in a low-permeability reservoir, especially in China. However, improving the life, reliability, and performance of the submersible linear motor and reducing energy consumption are challenging. Several novel designs for lubrication, hydraulic buffer, floating suction device, automatic motor drive, and control methods were proposed. The technology is simple to implement and can be adapted to low-production wells, directional wells, and horizontal wells. Introduction Rod pumping is a conventional oil-lift method in China, with more than 80% of oil wells across the country using this technique. However, conventional systems are more suited to high-production wells (e.g., in the range of 5–100 m3/d) than to low-fluid-yield wells. Conventional systems have high energy consumption and low efficiency when applied to low-fluid-yield wells such as directional, deviated, or sidetracked wells. Therefore, a rodless pumping technique was developed. In China, approximately 20% of the oil wells use rodless pumping with a nonlinear (rotary) motor, representing 30% of the country’s oil production and accounting for approximately one-third of total energy consumption in oil production. Compared with rod pumping, the rodless technique has lower associated materials costs, less risk, and no issues caused by the accidental dropping of rods and the eccentric wear associated with the conventional rod-pumping method. Either rotary or linear motors can be used in rodless pumping. The linear motor is a relatively new type of electric motor. The linear motor has its stator and rotor in linear motion to produce a linear force along its length. It is designed to convert electrical energy directly into linear mechanical energy. Although linear motors have been traced back to the 19th century, they are not widely used. Linear motors have been advanced and have proved to be economically viable for industrial application. In 2001, North China Oilfield Company experimented with the linear-motor-pumping technique. The linear-motor-pumping device used a downhole linear motor to lift the oil by reciprocating movement.

The hydrostatic gradient, not light availability, drives height‐related variation in Sequoia sempervirens (Cupressaceae) leaf anatomy

Leaves at the tops of most trees are smaller, thicker, and in many other ways different from leaves on the lowermost branches. This height-related variation in leaf structure has been explained as acclimation to differing light environments and, alternatively, as a consequence of hydrostatic, gravitational constraints on turgor pressure that reduce leaf expansion. • To separate hydrostatic effects from those of light availability, we used anatomical analysis of height-paired samples from the inner and outer tree crowns of tall redwoods (Sequoia sempervirens). • Height above the ground correlates much more strongly with leaf anatomy than does light availability. Leaf length, width, and mesophyll porosity all decrease linearly with height and help explain increases in leaf-mass-to-area ratio and decreases in both photosynthetic capacity and internal gas-phase conductance with increasing height. Two functional traits-leaf thickness and transfusion tissue-also increase with height and may improve water-stress tolerance. Transfusion tissue area increases enough that whole-leaf vascular volume does not change significantly with height in most trees. Transfusion tracheids become deformed with height, suggesting they may collapse under water stress and act as a hydraulic buffer that improves leaf water status and reduces the likelihood of xylem dysfunction. • That such variation in leaf structure may be caused more by gravity than by light calls into question use of the terms "sun" and "shade" to describe leaves at the tops and bottoms of tall tree crowns.