Simulation research on dynamic performance of the new type high-pressure solenoid valve

To improve energy density, the transportation, storage, and operations of hydrogen, methane, and compressed air vehicles currently require high-pressure compression. High-pressure solenoid valve becomes the vital element to above system. In order to reduce leakage and aerodynamic force influence, a new type high-pressure solenoid valve was proposed. The simulation model which included electromagnetic model, aerodynamic force model was established by means of the nonlinear mathematic models. Using the software MATLAB/Simulink for simulation, the dynamic response characteristics of high-pressure pneumatic solenoid valve were obtained under different pulse width modulation (PWM) input control signals. Results show that, first of all, the new type of high-pressure solenoid valve can meet the switch requirement. Secondly, the opening movement and closing movement of the spool lags the PWM rising signal, and the coil current fluctuates significantly during the movement of the spool. Lastly, on/off status of high-pressure valve cannot be represented by the duty cycle. This research can be referred in the design of the high-pressure solenoid valve..

Robust Sliding Mode Control for a 2-DOF Lower Limb Exoskeleton Base on Linear Extended State Observer

For the 2- Degree of Freedom (DOF) lower limb exoskeleton, to ensure the system robustness and dynamic performance, a linear-extended-state-observer-based (LESO) robust sliding mode control is proposed to not only reduce the influence of parametric uncertainties, unmodeled dynamics, and external disturbance but also estimate the unmeasurable real-time joint angular velocity directly. Then, via Lyapunov technology, the stability of the corresponding LESO and controller is proven. The appropriate and reasonable simulation was carried out to verify the effectiveness of the proposed LESO and exoskeleton controller.

Experimental Simulation and Verification of Position Servo Control of Mechanical Rodless Cylinder

In order to improve the position control accuracy of rodless cylinder, the valve control cylinder system based on pneumatic proportional servo is studied deeply. According to the working principle of the mechanical rodless cylinder control system, under the condition of uniform speed, the driving voltage of the proportional valve is changed to measure multiple sets of friction force and corresponding velocity data. Analyzed the physical structure of each component in pneumatic system, established the mathematical model of pneumatic system, and introduced MATLAB system identification toolbox to identify the parameters of the transfer function. and the experiment verifies its correctness.

Integration of measurement and simulation of film pressure for estimating deformation of a glass sheet on a noncontact air conveyor

Recently, large and thin glass substrates are transported by air film conveyors to reduce surface damage. On the production line, the glass substrates are desired to be transported flatly on the conveyor to ensure the quality inspection. A method by feedbacking film pressure to the theoretical model is proposed for estimation of the deformation of the glass sheet, and the validity of the method is theoretically and experimentally verified. First, a theoretical model including the flow behavior through a porous-walled gap is established, and the film pressure distribution can be predicted by solving the model. Then, an experimental setup that can simultaneously measure the film pressure and the flatness of the glass sheet is established, and, the validity of the model is verified experimentally. Next, with the pressure points at the grooves as the boundary and the pressure points at the flange area as the feedback, an algorithm is applied to shape the one-dimensional deformation at the centerlines in accordance with a quadratic curve. Furthermore, two-dimensional deformation of the glass sheet can then be estimated by an interpolation operation. Comparisons of the calculated results with the experimental data verify the effectiveness of the estimating method.

Dynamic optimization analysis of hydraulic pipeline system based on a developed response surface method

When designing a complex pipeline with long distance and multi-supports for offshore platform, it is necessary to analyze the vibration characteristics of the complex pipeline system to ensure that there is no harmful resonance in the working conditions. Therefore, the optimal layout of support is an effective method to reduce the vibration response of hydraulic pipeline system. In this paper, a developed dynamic optimization method for the complex pipeline is proposed to investigate the vibration characteristics of complex pipeline with multi-elastic supports. In this method, the Kriging response surface model between the support position and pipeline is established. The position of the clamp in the model is parameterized and the optimal solution of performance index is obtained by genetic algorithm. The number of clamps and the interval between clamps are considered as the constraints of layout optimization, and the optimization objective is the natural frequencies of pipeline. Taking a typical offshore pipeline as example to demonstrate the effectiveness of the proposed method, the results show that the vibration performance of the hydraulic pipeline system is distinctly improved by the optimization procedure, which can provide reasonable guidance for the design of complex hydraulic pipeline system.

Wind Turbine Speed Compound Control of a New-Type Wind-Electric Hybrid Power Pumping Unit

Because the load of the oil beam pumping unit driven by pure electric motor changes sharply during operation, the power of the driving motor does not match and the energy efficiency is low. In this paper, a new type of wind-driven hydro-motor hybrid power system is proposed. The motor and the hydraulic motor are jointly driven, and the energy is recovered by a hydraulic pump with controllable displacement, so that the speed of the driving motor is relatively stable. In order to control the fan speed and keep up with the drastic changes of the outside wind speed, a control strategy of hybrid power system based on wind speed feed-forward compensation is proposed. Through simulation and experimental results, the following conclusions can be drawn: to begin with, the mathematic model is proved to be effective; next, simulation studies show that the proposed feed-forward control method can improve the response rate as well as reduce the response lag. This research can be a reference for the application of the feed-forward control method on the hybrid power system of beam pumping unit.system.

Vibration Frequency Characteristic Study of Two-stage Excitation Valve Used in Vibration Experiment System

To satisfy the demands of higher frequency and amplitude in hydraulic vibration experiment system, the two-stage excitation valve is presented, and a mathematical model of two-stage excitation valve is established after analyzing the working principle of two-stage excitation valve, then the influence of relevant parameters on the displacement of main spool of two-stage excitation valve is studied by using Matlab/Simulink to calculate and analyze. The results show that the displacement of main spool will be smaller with bigger diameter and more secondary valve ports. When the reversing frequency is higher and the oil supply pressure is lower as well as the axial guide width of valve ports is smaller, the maximum displacement of main spool is smaller. The new two-stage excitation valve is easy to adjust reversing frequency and flow. The high frequency can be achieved by improving the rotation speed of servo motor and adding the number of secondary valve ports; the large flow can be realized by increasing the axial guide width of secondary valve ports and oil supply pressure. The result of this study is of guiding significance for designing the rotary valve for the achievement of higher reversing frequency and larger flow.

Modeling size-dependent behaviors of axially functionally graded Bernoulli-Euler micro-beam

This work focus on the mechanical behaviors, which are related to the size effect, functionally graded (FG) effect and Poisson effect, of an axially functionally graded (AFG) micro-beam whose elastic modulus varies according to sinusoidal law along its axial direction. The displacement field of the AFG micro-beam is set according to the Bernoulli-Euler beam theory. Employing the modified couple stress theory (MCST), the components of strain, curvature, stress and couple stress are expressed by the second derivative of the deflection of the AFG micro-beam. A size-dependent model related to FG effect and Poisson effect, which includes the formulations of bending stiffness, deflection, normal stress and couple stress, is developed to predict the mechanical behaviors of the AFG micro-beam by employing the principle of minimum potential energy. The mechanical behaviors of a simply supported AFG micro-beam are numerically investigated using the developed model for demonstrating the size effects, FG effects and Poisson effects of the AFG micro-beam. Results show that the mechanical behaviors of AFG micro-beams are distinctly size-dependent only when the ratio of micro-beam height to material length-scale parameter is small enough. The FG parameter is an important factor that determines and regulates the size-dependent behaviors of AFG micro-beams. The influences of Poisson’s ratio on the mechanical behaviors of AFG micro-beams are not negligible, and should be also considered in the design and analysis of an AFG micro-beam. This work supplies a theoretical basis and a technical reference for the design and analysis of AFG micro-beams in the related regions.

Design and Engineering Application of Direct Mixing Lubrication System for Emulsion Pipeline in Secondary Cold Rolling Mill

With the benefit fierce competition in the steel industry market in recent years, double cold reduction products have been developed towards strength improvement and thickness reduction. The traditional cold-rolling lubrication process with a fixed flow rate and concentration cannot solve the problems which cover uncontrollable shape of strip product and the excessive consumption of lubricating oil. Moreover,based on the analysis of the traditional direct application lubrication system of double cold reduction, a set of design scheme suitable for the emulsion pipeline direct mixing lubrication system of double cold reduction unit is proposed.The design complete the selection of key components which include the static mixer and atomization nozzle selection, pump and oil pump design selection, pipeline design selection, flow type selection, pressure gauge selection, electronic control cabinet design selection and other aspects. Equipment of the emulsion pipeline direct mixing lubrication system of double cold reduction has been developed. Comparing with characteristics of the traditional direct aplication lubrication system, the emulsion pipeline direct mixing lubrication system was better applied to the production practice of a 1220 double cold reduction mill. The consumption of ton of steel was reduced by 9.6%. The rolling energy consumption and oil consumption comprehensive costs decreased by 10.7%, and the strip steel section thickness difference was reduced by 19.3%. In addition, the plate shape quality defect rate decreased by 25.6 %, otherwise creating a large economic benefit for the unit and promoting the application value.

Seeding Performance Simulations and Experiments for a Spoon-Wheel Type Precision Cottonseed-Metering Device Based on EDEM

To study the effects of seed metering on seeding performance under different motion parameters, a simulation model for a spoon-wheel type seeder was established. A seed meter was tested by using EDEM (Engineering Discrete Element Method) software to simulate its working process at different speeds and tilt angles. The trajectories of individual cottonseeds in the seed-metering device were obtained, concurrently, the stress trend in the grain group was determined as a function of time. The simulation results suggest that at larger speeds, the metering index of the seed meter gradually decreases, while the index and the missing index gradually increase. As the tilt angle increased, the multiples index and missing index gradually decreased, while the multiples index gradually increased. When the seed meter speed reached 50 r/min and the tilt angle was 15°, the seed meter had a relatively good working performance with a seed spacing acceptance index of 92.59%, a multiples index of 1.85%, and a missing rate index of 5.56%. The seed meter was tested on a bench by using a JPS-12 performance-tester bench. At the aforementioned speed and angle, the coefficient of variation for the cottonseed spacing was 2.1%. The field trial results indicated that the multiples and the missing rates were higher than those for the tester bench but still met a passing rate of more than 90%. The coefficient of variation for the seed spacing was less than 10%, suggesting that the design could be used for field sowing. The resulting seeding uniformity was higher under these conditions, which indicates that the seed meter has a better working performance and the bench has a good seeding effect.