An algorithm is proposed for calculating a closed volumetric hydraulic pump-hydraulic motor system using the example of the hydraulic system of a wind power plant, based on the calculation of the hydraulic systems of mobile machines. The main characteristics of the system components, the selection of initial data for the calculation, working fluid and diameters of hydraulic lines are analyzed.
Keywords: hydraulic system, energy, fluid, oil, pump, motor, renewable energy source, wind power plant, machine.
[email protected]
Asymmetrical servo-hydraulic systems are commonly used in industry. These kinds of systems are nonlinear in nature and generally difficult to control. Because of changing system parameters, using the same gain will cause overshoot or even loss of system stability. The highly nonlinear behavior of these devises makes them idea subjects for applying different types of sophisticated controllers. This paper is concerned with using two artificial neural networks in compensation the dynamics and position tracking of a second order model reference in a flexible servo-hydraulic system. In present study, a neural network as an acceleration feedforward and another one as a gain scheduling of a proportional controller are proposed. Differential evolution algorithm is used to find the weights and biases to avoid the local minima. The proposed controller was verified with a commonly used p-controller. The results suggest that if the neural networks choose and train well, they improve all performance evaluation criteria such as stability, fast response, and accurate reference model tracking in servo-hydraulic systems.
The present study constructs a servo–hydraulic system to simulate the filling and packing processes of an injection molding machine. Experiments are performed to evaluate the velocity and position control of the system in the filling stage and the pressure control in the packing stage. The results demonstrate that the proposed system meets the required performance standards when operated with the proportional-integral–derivative (PID) controller under a sampling frequency of 1000 Hz.
A method which utilizes the power bond graph to establish the flexible hose model is described in this work. By using this method, the paper establishes mathematical modeling for the location of electro-hydraulic proportional control system with the flexible hose. And then, this article completes dynamic simulation by MATLAB and analyses the results of simulation. The effect of the flexible hose parameters on dynamics characteristics of the hydraulic system is also studied.
In structural modeling of launch vehicles, liquid propellant is sometimes rigidly attached to feedline walls. This assumption precludes the interaction of structural modes with propellant pressure and flow. An analysis of fluid-structure interaction (FSI) for the Atlas V launch vehicle revealed that structural models with rigidly-attached propellant yield unconservative response predictions under some conditions. In particular, during the maximum acceleration time of flight, pressure oscillations acting at bends in the Atlas V liquid oxygen (LO2) feedline excite 15–20 Hz structural modes that have considerable gain on the feedline and at the spacecraft interface. The investigation also revealed that the venting of gas from the pogo accumulator is an excitation source and changes the dynamic characteristics of the hydraulic system. The FSI simulation produced during the investigation can be adapted to mission-specific conditions, such that responses and loads are conservatively predicted for any Atlas V flight.
In order to study the tribological properties of different hydraulic oils under different motion modes, four-ball tester and block-on-ring tester were used to optimize the test parameters and evaluate performance of commercial hydraulic oils. The results showed that the optimized test methods under the form of point and line motion modes can better evaluate the extreme pressure and anti-wear performance of hydraulic oi. There was a negatively correlation between extreme pressure and anti-wear performance; this method can provide a basis for the reasonable selection of lubricating oil in hydraulic system.
Design and simulation of hydraulic system for launch vehicle holding device