Bio: Lijie Yang is an academic researcher from Beijing University of Technology. The author has contributed to research in topics: Torque sensor & Axial piston pump. The author has an hindex of 1, co-authored 1 publications receiving 20 citations.
TL;DR: In this paper, an integrated torque model for a swash-plate-type seawater hydraulic axial piston motor with symmetrical precompression angles has been developed, which consists of a torque submodel and a dynamic pressure sub-model.
Abstract: Seawater hydraulic axial piston motor is an important and elemental component in underwater tool system. The torque characteristics for a swash-plate-type seawater hydraulic axial piston motor is investigated, and an integrated torque model for the motor with symmetrical pre-compression angles has been developed, which consists of a torque sub-model and a dynamic pressure sub-model. Numerical simulations have been carried out to examine the effects of (a) pre-compression angle, (b) relief-groove obliquity, (c) motor speed, (d) piston chamber dead volume, (e) friction on the dynamic pressure and the output torque characteristics. The results indicate that the pre-compression angle, the friction coefficient, and the clearance between cylinder bore/piston have significant impact on the torque characteristics. The test verification has been undertaken with a five piston water hydraulic motor. This research contributes to the mechanism of output-torque fluctuation in a swash-plate-type seawater hydraulic axial piston motor, as well as the investigation of the torque transition phenomenon owing to the pre-compression angle. The research has laid the foundation for the development and improvement of the seawater hydraulic axial piston motor in underwater tool system.
TL;DR: In this article, a thermal-fluid-structure coupling analysis for valve plate friction pair of axial piston pump in electrohydrostatic actuator (EHA) of aircraft is presented.
Abstract: This paper deals with thermal-fluid-structure coupling analysis for valve plate friction pair of axial piston pump in electrohydrostatic actuator (EHA) of aircraft. The axial piston pump with high pressure and high rotational speed to be widely applied in EHA of more electric aircraft can increase the power density, but it also deteriorates thermal-fluid-structure coupling of the friction pairs. In order to reveal its interior multiphysics field coupling mechanism, taking the valve plate friction pair in three key friction pairs for example, this study carries out the research on multiphysics field coupling. Firstly, Navier–Stokes equations and energy equation of the incompressible fluid considering the influence of temperature and pressure on the oil properties, heat conduction governing equation with many boundary conditions including heat flux, heat convection, heat radiation and considering the influence of the structure deformation on the temperature and the influence of the temperature on the material properties, the elastic mechanics model of the structure exerted together by temperature, fluid pressure and mechanical load, are established. On this basis, a complete set of fast and effective thermal-fluid-structure coupling method is originally presented, and the numerical analysis is conducted using it for the valve plate friction pair. By the calculation results, the evolution laws with time and space are revealed regarding to the pressure and temperature of the fluid in the chambers, and the temperature, stress and deformation of the valve plate friction pair, the wedge-shaped clearance forms between them, even mixed friction occurs, and the corresponding improving measures aimed at the discovered problems are discussed. These results can provide the theoretical evidence for the design and development of the pump of EHA.
TL;DR: In this paper, the authors highlight an approach whereby the pressure fluctuations are absorbed by a larger external volume of compressed air, which reduces thermal losses to the surroundings and results in a highly efficient energy storage system.
Abstract: Despite the ability of accumulators to smooth out fluctuations in small-scale hydraulic circuits, their use in multi-megawatt power transmission systems remains limited This is due to the large pressure variations that they experience as their state-of-charge changes when their energy capacity is large The present work highlights an approach whereby the pressure fluctuations are absorbed by a larger external volume of compressed air This system has been integrated into a novel floating platform for offshore applications A thermodynamic model of the gas compression process is developed in order to observe temperature and pressure fluctuations A brief parametric analysis is undertaken to illustrate the effect of critical system dimensions This comprises the effect of the external volume with respect to the accumulator volume and the diameter of the umbilical connecting the two components The system is also simulated in different climates to observe the interaction between the external seawater temperature and the internal gas thermodynamics A full charge-discharge cycle is simulated and results indicate that around 95% of the energy can be recovered after being stored for a 24-h period The operational efficiency for a stochastic energy input was also computed and found to be relatively high Electrical round-trip efficiency was found to be comparable to adiabatic and near-isothermal CAES, but the system can be more advantageous when integrated into the generation-side The key attribute is the minimization of pressure fluctuations, which results in minimal deviations from the equilibrium temperature This reduces thermal losses to the surroundings and results in a highly efficient energy storage system
TL;DR: The experimental results show that the proposed anti-noise 1-D CNN model with multi-channel inputs can achieve 15% higher recognition accuracy than its counterpart with single-channel input on a testing set with SNR = 5 dB.
Abstract: Raising rotational speed is an effective way to improve power density of axial piston pumps, but high rotational speed tends to cause undesirable cavitation in the pump. Although some machine learning methods have been successfully applied to detect the cavitation with high accuracy, these conventional methods suffer from the drawback of time-consuming and experience-dependent manual feature extraction. In this paper, a new model based on 1-D convolutional neural network (CNN) is proposed to recognize the cavitation intensity of axial piston pumps. To improve the recognition accuracy under noisy environment, the 1-D CNN receives multi-channel vibration data instead of single-channel data. The experimental results show that the proposed anti-noise 1-D CNN model with multi-channel inputs can achieve 15% higher recognition accuracy than its counterpart with single-channel input on a testing set with SNR = 5 dB.
TL;DR: Considering the deformation of a designed seawater direct-acting relief valve (SDARV) in deep-sea environment, which has a significant influence on the dynamic performance, the mathematic model of SDARV was established and related dynamic characteristic simulations were conducted.
Abstract: Considering the deformation of a designed seawater direct-acting relief valve (SDARV) in deep-sea environment, which has a significant influence on the dynamic performance, the mathematic model of SDARV was established and related dynamic characteristic simulations were conducted. Since the fit clearance between damping spindle and damping bush is the key parameter affecting the dynamic characteristic of SDARV, the different fit clearances against varying depths were studied by ANSYS Workbench. The variations of seawater properties at different sea depths were also introduced to investigate the effect. From this study, the valve's dynamic performance after optimization in deep-sea environment was researched by MATLAB and the effective sea depth suiting for normal work was got. The results indicated effective dynamic performance of the SDARV within the depth of 1700 m and the optimum fit clearances after deformation should be kept in the range of 0.019 mm to 0.045 mm in deep sea environment.
TL;DR: In this paper, the authors developed a non-probabilistic reliability convex model for the valve-port plate pair, where the rotation of the pump cylinder was partitioned into six stages and the dynamic models of contact pressure and pv value were derived by accounting for the precompression angle.
Abstract: Seawater hydraulic axial piston pumps are widely used in underwater apparatus systems in recent years. Reliability of the valve-port plate pair is vital to the performance of seawater hydraulic axial piston pumps. As the distribution information of the material combinations and working conditions of seawater hydraulic axial piston pumps are insufficient, the probability reliability analysis methods are not available for the valve-port plate pair. This paper develops a non-probabilistic reliability convex model for the valve-port plate pair. Firstly, the rotation of the pump cylinder is partitioned into six stages. Based on this partition, the dynamic models of contact pressure and pv value (the product of contact specific pressure and linear velocity) of the valve-port plate pair are derived by accounting for the pre-compression angle. Secondly, the marginal interval for the limiting [pv] value (It is the usual criterion to evaluate the critical operating conditions under which the material fails) of the material combination was obtained through adhesive wear tests. Thirdly, a limit-state function is then established based on the stress-strength interference model. Finally, the analysis and sea test results indicate that the reliability of the valve-port plate pair has significantly improved by adding auxiliary support on the port plate.