The influence of dynamic swash plate vibration on outlet flow ripple in constant power variable-displacement piston pump

2019 ◽  
Vol 233 (14) ◽  
pp. 4914-4933 ◽  
Author(s):  
Yang Pan ◽  
Yibo Li ◽  
Dedong Liang
Keyword(s):  
Theoretical Model ◽  
Piston Pump ◽  
Plate Vibration ◽  
Axial Piston Pump ◽  
Constant Power ◽  
Flow Ripple ◽  
Swash Plate ◽  
Variable Displacement ◽  
Outlet Flow ◽  
Axial Piston

The vibration of a swash plate is caused by the piston forces and the control actuator acting on the swash plate. An earlier study of the outlet flow ripple of variable-displacement axial piston pumps assumed a fixed swash plate angle; it ignored the influence of swash plate vibration on the outlet flow ripple of the axial piston pump. In this work, a theoretical model of the outlet flow ripple and pressure pulsation was established in a constant power variable-displacement piston pump. The vibration of swash plate, flow leakage, and valve dynamic characteristics are considered in the theoretical model. The computational results of the theoretical model at different external load pressures are verified by comparison with experimental results. The vibration of the swash plate is strongly influenced by both the piston chamber pressure variation and the control actuator mechanism. The study proved the influence of the swash plate vibration on the outlet flow ripple and the pressure pulsation of an axial piston pump. Compared to the case of a fixed swash plate angle, accounting for swash plate vibration is much more suitable for the accurate determination of the outlet flow ripple and pressure pulsation of an axial piston pump. It is also shown that the vibration of the swash plate affects the valve plate design. Accordingly, valve plate optimization based on the theoretical model of the outlet flow ripple was also studied in this work. The amplitude of the instantaneous outlet flow ripple was considered as the optimization objective function. Finally, the optimized design parameters for a constant power variable-displacement swash plate axial piston pump were evaluated.

Kinematic Analysis of a Swash-Plate Controlled Variable Displacement Axial-Piston Pump With a Conical Barrel Assembly

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Zhiru Shi ◽  
Gordon Parker ◽  
Jonathan Granstrom
Keyword(s):  
High Pressure ◽  
Frequency Analysis ◽  
Flow Rate ◽  
Piston Pump ◽  
Flow Ripple ◽  
Swash Plate ◽  
Piston Displacement ◽  
Output Flow ◽  
Variable Displacement ◽  
Axial Piston

Variable displacement, swash-plate controlled, axial-piston pumps are widely used in applications that require high pressure and variable flow rates. The pump consists of a rotating barrel assembly that houses several pistons in a circular array. A swash-plate is used to control the displacement of the pistons to adjust the output flow of hydraulic fluid. As the barrel rotates, the pistons slide along the angled swash-plate and draw oil from the supply and then discharge oil into the high pressure circuit. This results in an almost constant output flow rate. This paper analyzes the kinematics of a pump based on its geometry dependent characteristics. The analysis assumes an idealized case in which there is no oil leakage and the fluid is considered to be incompressible. It is revealed through the analysis that the piston displacement and the pump output flow are slightly increased by using a conical barrel. Instantaneous and mean flow rate equations are used to describe the output flow characteristics and flow ripple effect. The output flow rate ripple profile is found to be a function of both swash-plate angle and the conical barrel angle. A term defined as the flow rate uniformity coefficient is used to better quantify the flow ripple phenomenon. A frequency analysis is performed on the output flow rate and an additional order is found to be present when using a conical barrel pump versus one with a cylindrical barrel when the pumps have an odd number of pistons. Conical barrel piston pumps are found to have a slight increase in piston displacement, velocity, and acceleration relative to the rotating barrel frame of reference over a pump with a cylindrical barrel. This translates into an increase in the output flow rate for a conical piston pump under the same operating conditions. The conical barrel is also found to have a reduction in the rotational inertia allowing for faster angular acceleration. The presence of an extra order from a frequency analysis for a conical pump with an odd number of pistons has the potential to cause unwanted noise or vibration to the structure or components attached to the pump.

scholarly journals Pressure compensator design, simulation and performance evaluation of a variable displacement swash plate type axial piston pump

2021 ◽  
pp. 123-130
Author(s):  
Nitesh MONDAL
Keyword(s):  
Design Procedure ◽  
Maximum Flow ◽  
Piston Pump ◽  
Experimental Result ◽  
Axial Piston Pump ◽  
Output Pressure ◽  
Swash Plate ◽  
Variable Displacement ◽  
Axial Piston ◽  
Plate Type

This work presents a simple design procedure of a pressure compensator of a swash plate type variable displacement axial piston pump (VDAPP). The route of the work mainly focuses on static design through balancing the torque given by the pump pistons, rate cylinder and strok- ing cylinder on the swash plate during cut-in (maximum flow) and cut-off (minimum flow) pressure condition of the system with an objective of minimizing the output pressure ripples. The outcome in terms of pressure from the dynamic simulation of the designed compensator with pump has been compare with experimental result obtained from a reference commercial pump has compensator with duel spool. The model has been used for performance prediction for wide variations of the load valve area settings.

Impact of Valve Plate Design on Noise, Volumetric Efficiency and Control Effort in an Axial Piston Pump

2006 ◽  
Author(s):  
Ganesh Kumar Seeniraj ◽  
Monika Ivantysynova
Keyword(s):  
Volumetric Efficiency ◽  
Valve Plate ◽  
Piston Pump ◽  
Design Parameters ◽  
Axial Piston Pump ◽  
Control Effort ◽  
Flow Ripple ◽  
Swash Plate ◽  
Plate Design ◽  
Axial Piston

In designing an axial piston pump, lot of attention is given to the design of the valve plate. A well designed valve plate can reduce both flow pulsations as well as oscillating forces on the swash plate. In the presented study, a computational tool, CASPAR, has been used for investigating the effect of valve plate design on flow ripple (fluid borne noise), oscillating forces (structure borne noise) and volumetric efficiency. The impact of various valve plate design parameters such as precompression grooves, cross port, indexing and additional precompression volume will be presented using simulation results from CASPAR. The study also details how rate of pressurization and decompression inside the displacement chamber directly relate to the flow ripple, forces applied on swash plate and the control effort needed to stroke the swash plate. The effect of noise reduction techniques on volumetric efficiency will also be presented with simulated results.

A CFD Approach for the Simulation of an Entire Swash-Plate Axial Piston Pump Under Dynamic Operating Conditions

2020 ◽  
Author(s):  
Massimo Milani ◽  
Luca Montorsi ◽  
Gabriele Muzzioli ◽  
Andrea Lucchi
Keyword(s):  
Fluid Dynamic ◽  
Operating Conditions ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Real Component ◽  
The Real ◽  
Flow Ripple ◽  
Swash Plate ◽  
Sliding Interfaces ◽  
Axial Piston

Abstract The paper proposes a CFD approach for the simulation of a swash-plate axial piston pump including the full 3D geometry of the real component. Different meshing techniques are integrated in order to reproduce all the internal motions of the pump. The overset mesh procedure is used to simulate the dynamic evolution in regions’ shape and the variable orientation between parts in the piston-slipper ball joints while the alternating motion of the piston is accounted for by sliding interfaces with the neighboring regions. The multiple dynamics of the different moving elements are implemented in terms of superposing motions in order to reproduce the real position time histories as a function of the rotational speed and the swash plate inclination angle. The proposed numerical model includes all the leakages that characterize the coupling of the many components of the pump and nominal values are assumed (i.e. 10μm) throughout the entire simulation. A pressure-dependent fluid density approach is adopted to improve the performance prediction of the pump under real operating conditions. Moreover, the turbulent behavior of the flow is addressed by means of the two equation k-omega SST model. Therefore the proposed modeling approach highlights the capabilities to address any type of swash-plate axial piston pump in order to simulate the entire machine under dynamic operations; the numerical results are discussed in terms of flow ripple, pressure distribution and fluid-dynamic forces.

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