Seawater Hydraulic Pump Research Articles

Research on Seawater Hydraulic Internal Ball Gear Pump

With high demands for novel technologies in the marine mechatronic instrumentality and the limitations of the present hydraulic pumps, a novel bidirectional seawater hydraulic internal ball gear pump is proposed to accomplish the function of fluid power transmission and control. The proposed hydraulic pump can be used for hydraulic buoyancy control systems of underwater vehicles and different marine mechatronic equipment. In this paper, the model, the meshing and the flow characteristics of the internal ball gear pump are developed. The radial unbalance force of the pump, leakage, and flow pulsation are also analyzed. The new type of eccentric shaft-hole rotary sealing designed in this paper can eliminate axial leakage and is expected to improve volumetric efficiency, working pressure, and power density. Simulation and experimental results show that: (1) by using the concave/convex ball gears rather than the existing gears, the concave ball gear drives the convex ball ring to rotate, realizing energy transfer and conversion; (2) compared with the water hydraulic internal gear pump, the internal ball gear pump has excellent performance. Experimental results also show that when the speed is 1500 rpm, the maximum operating pressure can reach 7 MPa. At 2 MPa, its volumetric efficiency and flow can reach 75% and 0.189L/min, respectively. The outcomes of this study show that the proposed seawater hydraulic internal ball gear pump is effective and has a lot of potential.

Research on the Vibration Characteristic of a Seawater Hydraulic Piston Pump System and Vibration Reduction Approach

Seawater hydraulic piston pump has been widely used in ocean engineering and become a key power component for underwater equipment due to its inherent characteristic such as energy conservation and environment friendly. As one of the most important properties of seawater hydraulic piston pump, vibration would further determine the stability, reliability and stealth of underwater equipment. In this paper, the dynamic of a novel crankshaft seawater piston pump with gearbox are analyzed theoretically, illustrating the dramatically effect of the gearbox on the vibration characteristic of the seawater hydraulic piston pump. Then, a new type crankshaft seawater hydraulic piston pump system driven by a permanent magnet synchronous motor instead of asynchronies motor is proposed in order to eliminate the gearbox and improve the vibration characteristics. In addition, the vibration characteristic of this new type crankshaft seawater hydraulic piston pump system driven by asynchronous motor and permanent magnet synchronous motor are studied and compared experimentally. The experiment results indicate that the seawater hydraulic piston pump system driven by permanent magnet synchronous motor eliminating the gearbox has lower vibration acceleration level in comparison with the pump system driven by asynchronous motor and gearbox. The vibration acceleration level can be reduced from 7dB to 4.3dB. Driving the seawater hydraulic piston pump by permanent magnet synchronous motor instead of asynchronous motor is of benefit to eliminating the gearbox and reducing the vibration excitation source. Consequently, the vibration characteristic of the seawater hydraulic piston pump system driven by a permanent magnet synchronous motor is significantly improved.

Application of Fault Diagnosis of Seawater Hydraulic Pump Based on Transfer Learning

The working environment of seawater axial piston hydraulic pump is harsh, and it is difficult to diagnose due to insufficient fault database. In contrast, pumps of the same type but using hydraulic oil have an adequate fault database and are easy to diagnose. In view of the above situation, a fault diagnosis method of seawater hydraulic piston pump based on transfer learning is proposed. The method decomposes the original sampled fault signal by complementary ensemble empirical mode decomposition (CEEMD) to obtain the intrinsic mode function (IMF) that can characterize the original signal. The singular value decomposition (SVD) is performed on the IMF. Then, the obtained singular value is used as a feature parameter to construct a feature vector. The feature data of seawater hydraulic pump and oil pump are used as target data and auxiliary data to form training data. The training data is trained based on the iterative adjustment of the weight through the TrAdaBoost transfer learning algorithm. Finally, the results of diagnosis and classification are compared with traditional machine learning. When the number of training data is 5 groups, the accuracy of transfer learning is 30.5% higher than that of traditional machine learning. The results show that transfer learning has great advantages in the case of a small number of samples.

Research on the seawater-lubricated sliding bearing of a novel buoyancy-regulating seawater pump considering the working depth

ABSTRACT Seawater hydraulic pump is a key component in buoyancy regulation systems. In this paper, a novel full-water-lubricated three-plunger seawater pump was designed in which the plunger suction and drainage are driven by the crankshaft. For this structure, the sliding bearing that supports the crankshaft is a very important factor affecting the pump characteristics. The pressure flow model and the thermal coupling system model of the left/right sliding bearings were established, and the deformation of the left/right sliding bearings in the deep sea environment was analysed by ANSYS Workbench. The change of the fit clearance has a great influence on the work of the hydraulic pump. Different fit clearances at different seawater depths under different radius gaps are obtained. The results show that the fit clearance of the left/right sliding bearings decreases as the depth of the seawater increases. As the depth of the seawater increases, the sliding bearing is gradually changed from the frictional lubrication of the liquid to the boundary friction lubrication. With the increases of the radius gap, the working water depth of the hydraulic pump first increases and then decreases, and the optimal radius clearance and the optimal working depth are obtained.

Study on the influence of rubber isolator's dynamic stiffness on the dynamic behavior of seawater hydraulic piston pump

Rubber isolator is commonly used as vibration isolation device for piston pump, and the vibration of piston pump can be effectively reduced by adjusting the dynamic stiffness of rubber isolator. In this paper, in order to study the effect of rubber isolator's dynamic stiffness on the dynamic of seawater hydraulic piston pump (SWHPP), four kinds of rubber isolators with different dynamic stiffness were selected. An experimental modal analysis (EMA) experiment was conducted to study the influence of rubber isolator's dynamic stiffness on the natural frequency of SWHPP. The experimental results indicated that the natural frequency of the pump structure decreased as the dynamic stiffness of rubber isolator increased. Then, the influence of the rubber isolator's dynamic stiffness on the vibration of SWHPP was further studied, and conclusions can be obtained that: the vibration level of the pump decreases with the dynamic stiffness of rubber isolator increases. For the four kinds of rubber isolators, when the dynamic stiffness of rubber isolator is 5800N/cm, the vibration reduction effect of the isolator is the best, which reaching 38%. In addition, the dynamic stiffness of rubber isolator mainly affects the vibration of the pump in the frequency of 0–20 Hz.

Non-probabilistic reliability analysis and design optimization for valve-port plate pair of seawater hydraulic pump for underwater apparatus

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.

A transmissibility-based approach to identifying the dynamic behavior of a seawater hydraulic piston pump under pressure excitation

An investigation into the dynamic behavior of the piston pump is an important method to reduce its vibration and noise. In this paper, an approach to predict the dynamics of a seawater hydraulic piston pump (SWHPP) from output-only transmissibility measurements is introduced. In order to eliminate the harmonic interference generated by spindle rotation, the excitation in this method is the pressure which caused by the SWHPP operating at a constant speed and under different loading conditions. The first four modes of the SWHPP were estimated utilizing the method proposed in this paper, and the influence of the pressure on the dynamics of the SWHPP structure was further studied. The experimental results indicated that peak occurred around the frequency of 20 Hz, and the reason is that the estimated second-order natural frequency (19.8 Hz) is near to the frequency of 20 Hz which is the excitation frequency of the swash plate and the flat valve of the SWHPP. In addition, this method can identify modal parameters of the piston pump structure in the working state, so it can effectively predict the dynamic behaviors of the piston pump.

Tool profile design for the mold for machining the bush of cone screw seawater hydraulic pump

Design method of the tool profile for machining the mold was found to facilitate the casting or extrusion of the bush of cone screw seawater hydraulic pump within this paper. Mathematical expression of the theoretical tool profile was established, as well as equation of the contact line between mold and tool surface, based on meshing theory and coordinate transformation theory. As solving contact condition involves implicit functions and trigonometric functions, only with methods of numerical discretization analysis by using the fzero function to solve single-variable nonlinear equations, can the contact line trajectory and theoretical curve of tool profile be obtained quickly and accurately. The tool profile design for manufacturing the mold lays a foundation for the processing of pump bush.

Deformation Analysis of Stator of Opposed Biconinal Cone Screw Seawater Hydraulic Pump

Metal cone of the screw rotor and stator rubber bushings are the two main components of the opposed biconinal cone screw hydraulic pump for the seawater. The stator rubber bushing is not only a damageable element, but also the key component deciding the service life and efficiency of the pump. Up to date, none effective method has been found for testing the deformation and enforced state of the stators rubber under the real working condition. For the general conventional screw stator with uniform internal pressure at both ends of the stator bushing enforced and deformed almost the same, as to other case when the cone screw pump stator has rubbers with different cross-sectional size and thickness at its different end, the enforcing and deforming state at different end varies differently. The stator of the opposed biconinal cone screw hydraulic pump is studied in this paper for the case when the stator is uniformly enforced, using finite element analyzing software ANSYS-Workbench , this study concluded the stress, the strain and inner-figure deformation of the screw hydraulic pump stator, the stator rubber and the stator steel thimble. Besides, the characteristics and rules of opposed biconinal cone screw hydraulic pump deformation are summarized as well.

Development of a Multifunctional Abrasion and Friction Test Bench with High Ambient Pressure for Seawater Hydraulics

Seawater hydraulic pump, of which the performances and service life are highly dependent on the structural design and material selection of the friction pairs and sliding bearing, are the power componentof the seawater hydraulic systems. Based on the previous studies, a seawater abrasion and friction test bench with high ambient pressure (≧20MPa) is to be developed for deep-sea (≧2000m) application environments. The technical requirements are presented and comparison analyses have been made between two testing schemes: rotating cylinder-blockscheme and rotating swash-plate scheme. Details are presented on the designs of the three key friction pairs and sliding bearing of the rotating cylinder-block bench. This research provides a test bench for the design of key parts in deep-sea water hydraulic pump/motor and the studies of the related theories (such as the friction and wear theory, lubrication and bearing mechanism).

Three-Dimensional Modeling of Opposed Biconical Cone Screw High-Pressure Seawater Hydraulic Pump

The rotor and stator were major components of the opposed biconinal cone screw high pressure seawater hydraulic pump, which precision of design and manufacture was particularly high, and the combining status between the stator and rotor has a significant impact on the performance of the new type pump, so the related research on above problems are carried out. In order to satisfy the demands of design efficiency and manufacture decision, a fast and simple way was presented to model 3D cone screw and bushing. Three-dimensional space Cartesian coordinates of cone screw and bushing profile with MATLAB programming were obtained according to the cone screw and bushing surface equation and the design parameters,3D curves of cone screw and bushing with MATLAB were rendered, and the feature point space coordinates were imported to Pro/Engineer so as to build cone screw and bushing solid model. Finally, making virtual assembly and checking interference on the screw and the bushing were necessary. The proposed method can make the complex 3D modeling more accurate, feasible and efficient.

Three Dimensional Finite Element Interference Contact Analysis about Cone Screw and Bush of Opposed Biconinal Cone Screw High-Pressure Seawater Hydraulic Pump

The main components of the opposed biconinal cone screw high-pressure seawater hydraulic pump is the rubber bush and metal cone screw, and the interaction of the bush and cone screw is one of the main factors affecting the novel pump performance. The deformation and stress of the bush and cone screw under the initial interference is analyzed by the nonlinear finite element analysis. The analysis shows that: under the effect of the initial interference, large displacement is present to the radial surface of the cone screw, and the displacement of the radial surface mainly affects the displacement vector sum of the cone screw, and the deformation decreases gradually from the middle to the ends of the cone screw, while the cone screw is bending; the deformation in three direction of the bush is close to each other, but the location of the maximum displacement in each direction is different; with the shrink range increasing, the deformation of the cone screw and bush increases, but the deformation of the cone screw is much smaller than that of bush, so the deformation of the bush mainly affects the seal between the cone screw and bush, and the shrink range between the cone screw and bush decreases because of the deformation of the bush. Over the role of the interference force, the maximum von mises stress of the cone screw is an order larger than that of bush, and the maximum von mises stress both increases with the shrink range increasing; although shrink range is different, the location of the maximum von mises about the cone screw and bush is the same.

FINITE ELEMENT ANALYSIS ABOUT STATOR OF OPPOSED BICONINAL CONE SCREW HIGH-PRESSURE SEAWATER HYDRAULIC PUMP

The rubber bush of the stator is not only the damageable parts of the opposed biconinal cone screw high pressure seawater hydraulic pump, and the combining status between the stator and rotor has a significant impact on the performance of the new type pump, so the related research on above problems are carried out. The contact finite element equation of the shell and bush is established and the deformation and stress of the stator's space and plane's model under the force state are compared and analyzed with the finite element method, and discuss whether the plane model could replace the space model on the finite element analysis of the deformation and stress about the stator. The analysis shows that the deformation and stress of the stator's plane model and space model have much difference, so the plane model can't replace the space model on the research of the finite element analysis. http://dx.doi.org/10.5755/j01.mech.17.5.733

Study on a seawater hydraulic piston pump with check valves for underwater tools

The aim of this study is to develop a seawater hydraulic piston pump for the power pack of an underwater tool system. A pump with check valves and oil–water-separated structure was selected for the purpose of improving its tolerance to particles when applied in open-circuit system. A novel ‘anti-loosening’ structure was introduced for the piston/shoe assembly. To improve the anti-wear and anti-corrosion performances of the piston and sleeve pairs under seawater lubrication, carbon fibre-reinforced polyetheretherketone was injected as an inner of the sleeve, and synthesized WC was formed on the piston with improved surface hardness. The unbalance problem of the shaft assembly was solved based on Solidworks software by adjusting the centre of mass of the shaft to its rotation axis and making all the products of inertia close to zero for an arbitrary-given coordinate system in which one of its axes is at the rotation axis. Basic performances and reliability experiments for the pump were carried out on a test rig. The shaft assembly was verified by experiment to reach very desirable balance effect. The pump has relative high efficiency at 10 MPa rated pressure and 14 MPa maximum pressure. After 300 h durability test, neither excessive wear could be found for the piston/sleeve pairs as well as other parts in the pump, nor obvious performance degradation happened to the pump. The dynamic balancing method presented in this article provides an easy and effective way to solve the unbalance problem for a shaft with special structure and can be widely used in other rotating machines. New design on the seawater hydraulic pump was initially confirmed to be feasible, although further research needs to be conducted. The pump has been successfully applied in an underwater seawater hydraulic tool system.

Lubrication and tribology in seawater hydraulic piston pump

Water hydraulic systems have provoked major interest because of the human friendly and environmental safety aspects. Piston pump is one of the most frequently used hydraulic units in recent engineering technique. In water hydraulic piston pump, poor lubrication is more likely to happen than in oil hydraulic one because of difference in properties between water and oil. So there are some key problems such as corrosive wear and erosion, which are investigated briefly. Many new materials have been developed, which give longer life expectancies with water without corrosion and erosion. A new type of seawater hydraulic piston pumps with better suction characteristics had been developed at HUST. Much of this research has concentrated on new materials, structure and experiments, which are also specially introduced.

Study of the key problems in a water hydraulic piston pump and its applications

In recent years water hydraulic systems have become of major interest because of the human friendly and environmental safety aspects. The piston pump is one of the most frequently used hydraulic units in recent engineering techniques. In a water hydraulic piston pump, poor lubrication is more likely to happen than in a oil hydraulic one because of differences in properties between water and oil. There are some key problems, such as corrosive wear and erosion, which are briefly investigated in this paper. Many new materials have been developed, which give longer life expectancies in water without corrosion and erosion. Recently, a new type of seawater hydraulic piston pump with better suction characteristics had been developed at Huazhong University of Science and Technology, China. Much of this research has concentrated on new materials, structure and experiments, which are also specially introduced in this paper.

THE DEVELOPMENT AND PERSPECTIVE OF WATER HYDRAULICS

Water is environmentally friendly, nonflammable, inexpensive, clean, readily available, and easily disposable. As concerns for environmental compatibility, safety and hygienic requirements, hydraulic systems using raw water as pressure medium become more and more attractive. With the continual introduction of new materials and advanced manufacturing processes, hydraulic systems to operate with water have become practical. The history of pressure medium in hydraulic systems will be briefly reviewed, the advantages with water hydraulics are summarized and the main differences in physicochemical properties of water and oil are presented at first in this paper. Based on authors' research on seawater hydraulics, the main design challenges for developing water hydraulic components are analyzed. A new seawater hydraulic pump with better filling characteristics and a simulating test apparatus for testing the critical matching pairs in a seawater hydraulic pump (motor) developed at Huazhong University of Science and Technology, P. R. China, are introduced. An overview of the bright future for water hydraulics is indicated in this paper.