scholarly journals A Numerical Study on Influence of Temperature on Lubricant Film Characteristics of the Piston/Cylinder Interface in Axial Piston Pumps

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1842 ◽  
Author(s):  
Yueheng Song ◽  
Jiming Ma ◽  
Shengkui Zeng
Keyword(s):  
Thermal Effect ◽  
Contact Time ◽  
Numerical Study ◽  
Lubricant Film ◽  
Piston Pump ◽  
Pump Efficiency ◽  
Axial Piston Pumps ◽  
Piston Cylinder ◽  
Film Characteristics ◽  
Axial Piston

The loss of kinetic energy of moving parts due to viscous friction of lubricant causes the reduction of piston pump efficiency. The viscosity of lubricant film is mainly affected by the thermal effect. In order to improve energy efficiency of piston pump, this research presents a numerical method to analyze the lubricant film characteristics in axial piston pumps, considering the thermal effect by the coupled multi-disciplinary model, which includes the fluid flow field expressed by Reynolds equation, temperature field expressed by energy equation and heat transfer equation, kinematics expressed by the motion equation. The velocity and temperature distributions of the gap flow of piston/cylinder interface in steady state are firstly numerically computed. Then the distributions are validated by the experiment. Finally, by changing the thermal boundary condition, the influence of thermal effect on the lubricant film, the eccentricity and the contact time between the piston and cylinder are analyzed. Results show that with the increase of temperature, the contact time increases in the form of a hyperbolic tangent function, which will reduce the efficiency of the axial piston pump. There is a critical temperature beyond which the contact time will increase rapidly, thus this temperature is the considered as a key point for the temperature design.

scholarly journals A New Approach for Modeling Mixed Lubricated Piston-Cylinder Pairs of Variable Lengths in Swash-Plate Axial Piston Pumps

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5836
Author(s):  
Bo Zhao ◽  
Xinqing Hu ◽  
Haifeng Li ◽  
Yonghui Liu ◽  
Baocheng Zhang ◽  
...  
Keyword(s):  
Multibody Dynamics ◽  
Tilt Angle ◽  
Piston Pump ◽  
Dynamics Model ◽  
Axial Piston Pumps ◽  
Piston Cylinder ◽  
Cylinder Length ◽  
Swash Plate ◽  
Axial Piston ◽  
Multibody Dynamics Model

The swash-plate axial piston pump is one of the most widely used pumps due to its simplicity and compactness in structure. In such a pump, the piston-cylinder system plays a crucial role, with its lubrication characteristics greatly affecting the overall pumping performance. A new numerical approach is proposed in this study for modeling mixed lubricated piston-cylinder interfaces of variable lengths in swash-plate axial piston pumps in the framework of multibody dynamics. The approach couples the hydrodynamic mixed lubrication model of the piston-cylinder interface with the multibody dynamics model of the piston pump. The lubrication model is established with a transient average Reynolds equation considering asperity contacts and is solved with the finite element method to derive the hydrodynamic forces of the lubricated pair, while the multibody dynamics model is established with Lagrangian formalism by considering hydrodynamic forces as external forces. Results for piston-cylinder interfaces of variable lengths in swash-plate axial piston pumps are presented, and the impacts of cylinder length and the tilt angle of the swash plate on the tribological performances of the interface are discussed. The results indicate that increasing the cylinder length can improve the stability and wear resistance of the piston, but it can exacerbate the frictional power loss. Moreover, although enlarging the tilt angle of the swash plate can effectively increase pump displacement, it can easily lead to serious friction, wear, and leakage problems. Consequently, the tilt angle of the swash plate should be carefully selected in practical applications.

Improving the Volumetric Efficiency of the Axial Piston Pump

2012 ◽  
Vol 134 (11) ◽  
Author(s):  
Shu Wang
Keyword(s):  
Operating Conditions ◽  
Volumetric Efficiency ◽  
Valve Plate ◽  
Piston Pump ◽  
Efficient Design ◽  
Axial Piston Pumps ◽  
Definition Of ◽  
Engineering Practices ◽  
First Time ◽  
Axial Piston

The volumetric efficiency is one of the most important aspects of system performance in the design of axial piston pumps. From the standpoint of engineering practices, the geometric complexities of the valve plate (VP) and its multiple interactions with pump dynamics pose difficult obstacles for optimization of the design. This research uses the significant concept of pressure carryover to develop the mathematical relationship between the geometry of the valve plate and the volumetric efficiency of the piston pump. For the first time, the resulting expression presents the theoretical considerations of the fluid operating conditions, the efficiency of axial piston pumps, and the valve plate designs. New terminology, such as discrepancy of pressure carryover (DPC) and carryover cross-porting (CoCp), is introduced to explain the fundamental principles. The important results derived from this study can provide clear recommendations for the definition of the geometries required to achieve an efficient design, especially for the valve plate timings. The theoretical results are validated by simulations and experiments conducted by testing multiple valve plates under various operating conditions.

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.

scholarly journals Study on Film Characteristics of Piston-Cylinder Interface of High Pressure Common Rail Radial Piston Pump with Viscosity-Temperature-Pressure Effect

2019 ◽  
Vol 256 ◽  
pp. 02007
Author(s):  
Bo Qi ◽  
Yong Zhang ◽  
Guoyou Meng ◽  
Yao Ding
Keyword(s):  
High Pressure ◽  
Pressure Effect ◽  
Hydrodynamic Lubrication ◽  
Engineering Application ◽  
Basic Research ◽  
Common Rail ◽  
Piston Pump ◽  
Piston Cylinder ◽  
Film Characteristics ◽  
High Pressure Common Rail

Aiming at the inaccuracy of equivalent viscosity method in solving the film characteristics of piston-cylinder interface of high-pressure common rail radial piston pump, the film characteristics equation of piston-cylinder interface was established based on the theory of thermo-hydrodynamic lubrication. Through the solution, the thermal properties of the piston-cylinder interface film, which accounted for viscosity-temperature-pressure effect, were studied. The effects of cam speed and film inlet pressure on the characteristics of the piston-cylinder interface film were discussed. The conclusion has certain theoretical and engineering application value for the design and basic research of piston-cylinder interface.

Profiling the Discharge Channel Flow Part of Axial Piston Pump

2019 ◽  
pp. 53-64
Author(s):  
N.A. Belov ◽  
O.F. Nikitin
Keyword(s):  
Discharge Channel ◽  
Three Dimensional ◽  
Piston Pump ◽  
Working Fluid ◽  
Dynamic Parameters ◽  
Axial Piston Pump ◽  
Three Dimensional Model ◽  
Output Section ◽  
Axial Piston Pumps ◽  
Axial Piston

The article considers the flow of the working fluid in the discharge channel of the axial piston pump with end distribution. Geometric region shapes of the channels, currently used in axial piston pumps, negatively affecting the dynamic parameters of the flow flowing through it, are determined by numerical simulation. The configuration of the channel cavity allowing a more uniform distribution of dynamic parameters over the volume of the fluid flow is proposed. The optimal ratio between the reference dimensions adopted for constructing a three-dimensional model of the channel was determined based on the study of the dependence of the power factor value, the amount of movement in the output section vs the shape of the channel. Energy loss due to flowing the working fluid through the channel is reduced. The resulting force effect on the discharge pipe and other elements connected to the pump is reduced and the vibroacoustic characteristics of the pump unit are improved.

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