scholarly journals An Empirical Model for the Churning Losses Prediction of Fluid Flow Analysis in Axial Piston Pumps

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 398
Author(s):  
Ying Li ◽  
Xing Chen ◽  
Hao Luo ◽  
Jin Zhang
Keyword(s):  
Power Density ◽  
High Speed ◽  
Flow Analysis ◽  
Piston Pump ◽  
Cylinder Block ◽  
Axial Piston Pump ◽  
Axial Piston Pumps ◽  
Wide Range ◽  
Fluid Flow Analysis ◽  
Axial Piston

The manufacturing development of axial piston pumps usually takes the trend of high speed and miniaturization, and increases power density. Axial piston pumps are usually characterized as high speed to improve the power density; thus, high-speed churning losses caused by the internal rotating components stirring the oil can increase significantly. In order to improve the efficiency, more attention should be given to the churning losses in axial piston pumps, especially in high-speed conditions. Using the method of least-squares curve fitting, this paper establishes a series of formulas based on the churning losses test rig over a wide range of speeds, which enable accurate predictions of churning losses on the cylinder block and pistons. The reduction coefficient of flow resistance of multi-pistons as calculated. The new churning losses formula devoted to the cylinder block and rotating pistons was validated by comparison with experimental evidence in different geometries of axial piston pumps. According to the prediction model of churning losses, some valuable guidance methods are proposed to reduce the energy losses of the axial piston pump, which are the theoretical support for the miniaturization of axial piston pump manufacturing.

Improving accuracy of cavitation severity recognition in axial piston pumps by denoising time-frequency images

2022 ◽  
Author(s):  
Qun Chao ◽  
Xiaoliang Wei ◽  
Junbo Lei ◽  
Jianfeng Tao ◽  
Cheng-Liang Liu
Keyword(s):  
High Speed ◽  
Diagnostic Performance ◽  
Vibration Signal ◽  
Piston Pump ◽  
Noisy Environment ◽  
Axial Piston Pump ◽  
Denoising Method ◽  
Time Frequency ◽  
Axial Piston Pumps ◽  
Axial Piston

Abstract Vibration signal is a good indicator of cavitation in axial piston pumps. Some vibration-based machine learning methods have been developed for recognizing the pump cavitation. However, their fault diagnostic performance is often unsatisfactory in industrial applications due to the sensitivity of the vibration signal to noise. In this paper, we presented an intelligent method to recognize the cavitation severity of an axial piston pump under noisy environment. First, we adopted short-time Fourier transformation to convert the raw vibration data into spectrograms that acted as input images of a modified LeNet-5 convolutional neural network (CNN). Second, we proposed a denoising method for the converted spectrograms based on frequency spectrum characteristics. Finally, we verified the proposed method on the dataset from a test rig of high-speed axial piston pump. The experimental results indicate that the denoising method significantly improves the diagnostic performance of the CNN model under noisy environment. For example, the accuracy rate of the cavitation recognition increases from 0.52 to 0.92 at SNR of 4 dB by the denoising method.

The Suction Dynamics of Positive Displacement Axial Piston Pumps

1994 ◽  
Vol 116 (2) ◽  
pp. 281-287 ◽  
Author(s):  
R. M. Harris ◽  
K. A. Edge ◽  
D. G. Tilley
Keyword(s):  
High Speed ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Axial Piston Pumps ◽  
Positive Displacement ◽  
High Speeds ◽  
Suction Line ◽  
Pump Inlet ◽  
Suction Performance ◽  
Axial Piston

The suction dynamics of axial piston pumps become more critical if the pump is to be used at high speeds. In order to prevent air-release and cavitation from occurring within the pump it is necessary to pressurise the pump inlet. As the speed of a pump is increased, higher boost pressures are required, due to the extra losses incurred through the suction line and portplate at the higher flowrates. However, the lack of data regarding axial piston pump behavior at high speeds creates problems for the system designer in selecting suitable boost conditions and for the pump designer in selecting the portplate configuration that is required to reduce fluid-borne-noise levels. This paper discusses the suction performance of piston pumps, and presents experimental and simulation results exploring the behavior of a high-speed axial-piston pump. Different air-release and cavitation models that are suitable for simulation studies are investigated.

scholarly journals Novel design of hydrodynamic–magnetic compound support for cylinder block–valve plate in axial piston pump

AIP Advances ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 115221
Author(s):  
Jihai Jiang ◽  
Boran Du ◽  
Jian Zhang ◽  
Geqiang Li
Keyword(s):  
Valve Plate ◽  
Piston Pump ◽  
Cylinder Block ◽  
Axial Piston Pump ◽  
Axial Piston ◽  
Novel Design

Cavitation in a high-speed aviation axial piston pump over a wide range of fluid temperatures

2021 ◽  
pp. 095765092110469
Author(s):  
Qun Chao ◽  
Zi Xu ◽  
Jianfeng Tao ◽  
Chengliang Liu ◽  
Jiang Zhai
Keyword(s):  
Temperature Effects ◽  
Pressure Pulsation ◽  
Piston Pump ◽  
Limiting Factors ◽  
Fluid Temperature ◽  
Cfd Model ◽  
Axial Piston Pump ◽  
Wide Range ◽  
Fluid Properties ◽  
Axial Piston

The axial piston pump in aerospace applications needs to operate over a wide range of fluid temperatures from −54°C to 135 °C. The fluid properties at such extreme temperatures will significantly affect the cavitation that is one of the major limiting factors for the efficiency and reliability of aviation axial piston pumps. However, it appears that very little of the existing literature studies the effects of extreme fluid temperatures on the pump cavitation. This paper aims to examine the temperature effects on the cavitation in an aviation axial piston pump. First, we develop a three-dimensional (3D) transient computational fluid dynamics (CFD) model to investigate the pump cavitation and validate it experimentally. Second, we use the validated CFD model to investigate the temperature effects on the pump cavitation by changing the fluid properties including viscosity, density, and bulk modulus. The numerical results show that low fluid temperature makes the aviation axial piston pump suffer serious cavitation due to high viscosity, leading to delivery flow breakdown, unacceptable pressure pulsation, and delayed pressure built up. In contrast, high fluid temperatures have minor effects on the cavitation although they increase the pressure pulsation and built-up time slightly.

Analysis on the Side Leakage Amount of the Friction between Piston and Cylinder Block in Axial Piston Pump

2014 ◽  
Vol 635-637 ◽  
pp. 341-345 ◽  
Author(s):  
Wei Wang
Keyword(s):  
Flow Rate ◽  
Piston Pump ◽  
Cylinder Block ◽  
Correction Coefficient ◽  
Leakage Flow ◽  
Fluid Viscosity ◽  
Axial Piston Pump ◽  
Viscosity Change ◽  
Leakage Flow Rate ◽  
Axial Piston

The spherical distribution pairs of the plunger and the cylinder friction, has an important influence on the performance of spherical port plate axial piston pump. Based on the analysis of fluid viscosity change with pressure and temperature, considering friction differential pressure flow and shear flow, establishes the mathematics model of the friction pair of leakage. The simulation analysis using MATLAB software, the leakage flow rate is not proportional to pressure, but with the increase of pressure leakage flow was increased, and with the increase of pressure viscosity coefficient and temperature coefficient of viscosity, the leakage flow rate correction coefficient increases obviously, so in the choice of the hydraulic oil cylinder hole, should choose a relatively moving average leakage rate had no effect the piston ring slot.

Novel Piston Pressure Carryover for Dynamic Analysis and Designs of the Axial Piston Pump

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Shu Wang
Keyword(s):  
Piston Pump ◽  
Axial Piston Pump ◽  
Pump Performance ◽  
Axial Piston Pumps ◽  
Bottom Dead Center ◽  
Pump Pressure ◽  
Definition Of ◽  
And Control ◽  
Axial Piston ◽  
The Relationship

The timing definition of valve plates is one of the most complex topics in the piston pump designs because it affects many pump characteristics (such as efficiency, swashplate stroking, stabilities, noise, etc.). In the study, the pressure carryover is introduced and defined as the average angular positions to locate piston pressure transitions from the top dead center (TDC) or bottom dead center (BDC) in the piston pump. Pressure carryover presents the overall outcome of the pressure transitions within piston bores. The new pressure carryover definition is derived by the timing angles and other geometrics of valve plates that is an approximation of the practical pressure transitions. The pressure carryover also determines the containment forces and moments on the swashplate produced by the pumping pistons. The relationship between the pressure carryover angle and the containment moment has been developed and analyzed in the study. The amplitudes and frequencies of the forces and moments can be changed by varying the pressure carryover angle that produce different tonalities and control efforts for the swashplate type axial-piston pumps. Therefore, the pressure carryover is the most important and straightforward connection between pump dynamics and valve plate designs. In order to optimize the pump performance, the piston pressure carryover might be investigated thoroughly for the pump and its controller designs.

Discharge Flow Ripple of Axial Piston Pump with Conical Cylinder Block

2010 ◽  
Vol 34-35 ◽  
pp. 440-445
Author(s):  
Lei Li ◽  
Jian Ke ◽  
Jia Xu ◽  
Wang Yong
Keyword(s):  
Block Design ◽  
Cone Angle ◽  
Point Of View ◽  
Piston Pump ◽  
Cylinder Block ◽  
Axial Piston Pump ◽  
Discharge Flow ◽  
Flow Ripple ◽  
Displacement Pump ◽  
Axial Piston

The discharge flow ripple is a crucial criterion for evaluating the piston pump. This research examines the discharge flow ripple of axial piston pump with conical cylinder block by developing a comprehensive mathematical model based upon the Bernoulli equation and the continuity equation. The novel aspect of this research is that it includes the analysis of cylinder block cone angle. From the results of this research, it can be concluded that cylinder block cone angle has a significant impact on the discharge flow ripple, and utilizing a conical cylinder block design is more feasible than cylindrical cylinder block from a flow ripple point of view. This conclusion can be used to guide the up-front design for the variable displacement pump.

Development of Oil Hydraulic Components Using a Flow Visualization Technique

2012 ◽  
Vol 6 (4) ◽  
pp. 410-417 ◽  
Author(s):  
Tetsuhiro Tsukiji ◽  
◽  
Eishin Noguchi ◽  
Futoshi Yoshida ◽  
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Ball Valve ◽  
Piston Pump ◽  
X Rays ◽  
Axial Piston Pump ◽  
Visualization Technique ◽  
High Speed Video ◽  
High Speed Video Camera ◽  
Axial Piston

In the present study, we succeed in observing cavitating flow near a notch (V-shaped groove) in a valve plate in an axial piston pump, and we improve an oil hydraulic ball valve, using the visualization technique. Our model of the axial piston pump, is designed to allow the jet flow near the notch and the cavitation cloud to be observed clearly from two directions using a high-speed video camera. Computational Fluid Dynamics (CFD) is employed to estimate the occurrence and the region of the cavitation cloud. It is found that our CFD method is very useful for estimating the region of the cavitation cloud. It is further found that adding notches serves to greatly reduce the cavitation region. Using a commercially available digital video camera, a high-speed video camera, and X-rays source, we also succeed in improving an oil hydraulic ball valve by preventing vibration, cavitation, and the noise.

scholarly journals Tribological Properties of Cylinder Block/Valve Plate Interface of Axial Piston Pump on the Tribometer

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Jiahai Huang ◽  
Zhenhua Dou ◽  
Zhenglei Wang ◽  
Long Quan ◽  
Linkai Niu
Keyword(s):  
Heat Treatment ◽  
Contact Pressure ◽  
Tribological Properties ◽  
Optimization Design ◽  
Valve Plate ◽  
Piston Pump ◽  
Cylinder Block ◽  
Axial Piston Pump ◽  
Plate Interface ◽  
Axial Piston

AbstractThe tribological properties of cylinder block/valve plate is an important consideration in the design of axial piston pump. The effect of materials and heat treatment on friction and wear properties has been studied in depth. Engineering experiences show that the speed and load also affect the tribological properties, but these have not been systematically analyzed. The purpose of this paper is to evaluate the tribological properties of the commonly used materials (CuPb15Sn5 and 38CrMoAl/42CrMo) for cylinder block/valve plate with different heat treatment and contact pressure at different speed. During the test, tribometer is used to simulate the contact pattern between the valve plate/cylinder block in axial piston pump, the friction coefficient, wear rate and surface topography are analyzed to evaluate the tribological properties of different types of friction samples at different speed. Results indicate that: (1) contact surface of the samples at 1800 r/min is more prone to adhesive wear than those at 500 r/min; (2) in the terms of wear resistance, quench-tempered and nitrided 38CrMoAl (38CrMoAl QTN for short) is better than quench-tempered and nitrided 42CrMo, although they are all commonly used materials in the axial piston pump; (3) 2.5 MPa is the critical contact pressure of the interface between valve plate made of 38CrMoAl QTN and cylinder block made of CuPb15Sn5 on the tribometer, which implies the pressure bearing area at the bottom of the cylinder block should be carefully designed; (4) the valve plate/cylinder block made of 38CrMoAl QTN/CuPb15Sn5 exhibits good tribological properties in a real axial piston pump. This research is useful for the failure analysis and structural optimization design of the valve plates/cylinder block.

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