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Under consideration of the physical and chemical properties of water and water hydraulic transmission characteristics, the principle and structure of a new type of water hydraulic vane pump is provided in this paper. This pump has changed the vane's radial motion into the axial motion so that the size of the pump is reduced and has a feature of smooth displacement and low noise. Because it reduces...
The paper presents a control algorithm hydropneumatic system with smooth changes in the elastic characteristics of the impact of various kinds of dynamic and kinematic disturbances. We had made the analysis of the control object, which allowed us to offer a common structure of the automatic control system. Particular attention is paid to the description of control principles inherent in the computing...
The control problem under the condition of uncertainty is an important subject of modern control field. In most control problems, the actual control object and mathematical model for the controller design are always present differences. These differences come from the object parameter uncertainty and time-varying, etc. Mill hydraulic position servo system is the complex nonlinear control system with...
This paper describes the design and analysis of a direct load sensing electro-hydrostatic actuator (EHA) to solve the heating problem of the motor in current EHAs. The design utilizes load sensing technology to automatically adjust the variable displacement pump, so that the motor can work in the high efficiency area to reduce the heating. Especially it can significantly enhance the efficiency of...
According to the configuration evolution method, a parallel mechanism with three rotational degrees of freedom, which is driven by group of four pneumatic artificial muscles, was designed by removing two SPS branches of Stewart mechanism and adding constraint branch to constrain the three translational degrees of freedom of the moving platform. A parallel mechanism experimental table was established...
Modern robotic systems require the use of servo drives. These drives due to the position sensor and the negative feedback ensure high accuracy motion parameters. In the case of autonomous systems to the drives and places even high power characteristics. Moreover, in most cases, it is impossible to pick up the motor so that the speed and torque on its shaft to meet required actuator. To reconcile these...
Reducing the flow induced forces acting on the spool is necessarily important for the energy efficient operation and minimizing the stability problem in different types of spool valves. Aiming to reduce the steady flow force acting on the spool, a simple jet-guiding groove is proposed. It is V-groove created on the side face of the spool land. By means of Computational Fluid Dynamics (CFD) simulations,...
Cavitation in the flapper-nozzle pilot valve has been found as the mechanism of performance deterioration of the electro-hydraulic servo-valve. In this paper the transient cavitation patterns of the flapper-nozzle structure have been studied experimentally based on the Principle Components Analysis (PCA) method. Firstly the basic principle of PCA is introduced. Then a set of test images is used to...
Due to its fast dynamic response and low power consumption, torque motor valve is widely used in the foreign bipropellant thrusters to realize the switch control of propellants. China's bipropellant thruster uses two solenoid valves to control separately two propellants because of their simple structure and process. However, the dynamic response of the solenoid valve is far less than the torque motor...
Attempting to suppress high frequency resonant vibrations of a hydraulic servo-valve torque motor, vibration characteristics of armature assembly in the torque motor with and without magnetic fluids are studied in this paper. The mathematical model of the resistance force that the magnetic fluids acts on the armature is established. The equivalent physical model of magnetic fluids which is taken as...
Self-excited high frequency pressure oscillations in the flow field of a hydraulic servo-valve are usually the source of high frequency noise. In this paper, by using a piezoelectric dynamic pressure transducer and a microphone, the self-excited high frequency pressure oscillations and noise in a hydraulic jet-pipe servo-valve are measured. The experiments are carried out when the supply pressures...
Axial Piston Pumps(APPs) have been widely used in industrial and mobile applications. To improve the operation performance, it is important to reduce pressure pulsations and noise level of APPs. The present paper, by analyzing the actual operating conditions in engineering point of view, proposes an iteration method of finding the reference operating conditions for designing valve plates in APPs with...
The proposed paper deals with the problem of modelling and simulation of a dual-redundancy Electro-Hydrostatic Actuator (DREHA) by the way of co-simulation based on AMESim and MATLAB. With the development of More Electric Aircraft (MEA) technology, integrated Power-by-Wire (PBW) actuator will be used in the airborne actuation system. As an important PBW actuation system, EHA has virtues of high efficiency,...
Slotted filters are used for retaining solid particles during the fluid extraction from the well. In the present study a model of slotted filter is considered for hydraulic calculations. The force analysis is done for solid particles (the size is 0.2 (mm)) in a filtration flow in a well with installed slotted filter. Several cases of solid particle motion are observed. The direction of solid particle...
Transit condition is one of the most important conditions in the safety assessment of the self-elevated platform. Inertia load must be considered in this condition. Usually, the determination of the inertia load is carried out by an assumption of simple harmonic motion. But it is unknown whether this assumption is reliable. RAOs of the platform are solved by direct numerical method of linear potential...
In order to compare braking performance of dual torus hydrodynamic retarderwith different blades, the braking performances of dual torus hydrodynamic retarder with the bowed blade and different angle straight blades are calculated. The internal flow fields of different blade hydrodynamic retarder are numerically simulated by computational fluid dynamics (CFD) method. The braking torque, the distribution...
A large flow three position four-way cartridge servo valve formed by a number of parallel cartridge two-way servo valves is designed to deal with the contradiction between large flow and high-frequency of the electro-hydraulic servo valve. A cross-coupled synchronization fuzzy control based on synchronization error of double valve is proposed to solve the asynchronization problem during the working...
The traditional oil cooling method is replaced by the semiconductor refrigeration technology, the design of a new type of semiconductor refrigeration system is applied to oil source temperature control. The mechanism of semiconductor refrigeration is analyzed, hot and cold end temperature difference of the device (Th-Tc) and the figure of merit of thermoelectric materials Z influence on the performance...
As a noncontact auxiliary brake system used in heavy-duty vehicles or buses, hydrodynamic retarders dissipate kinetic energy to heat energy with adjustable braking levels by mixing given different ratios of hydraulic oil and air, or liquid-filled ratio, into the flow passages in its flow passages in rotors and stators. During the transient braking process, flow separations and secondary flows are...
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