Dynamic Analysis of an Axial Piston Pump Swashplate Control

1986 ◽  
Vol 200 (1) ◽  
pp. 49-58 ◽  
Author(s):  
G Zeiger ◽  
A Akers
Keyword(s):  
Control Volume ◽  
Damping Ratio ◽  
Low Frequency ◽  
Operating Conditions ◽  
Piston Pump ◽  
State Variables ◽  
Axial Piston Pump ◽  
Basic Parameters ◽  
Experimental Values ◽  
Axial Piston

A mathematical model of an axial piston pump is described which consists of a second-order differential equation of the swashplate motion and two first-order equations describing the flow continuity into the pump discharge chamber and into the swashplate control actuator. The equation of the swashplate angle contains torque components due to operating states. A method is presented by which the average torque can be computed for a pump of given geometry and at any given set of operating conditions. From the calculated average torque, the coefficients of the basic equation can be evaluated; agreement to within 10 per cent of experimental values for torque has been achieved. A state variables analysis of the dynamic behaviour has shown that there are two dominant poles at low frequency and that the damping ratio associated with these poles reduces by approximately one half when the downstream control volume increases by a factor of three, and varies from 0.84 to 0.48 as the pump rotational speed increases from 126 to 209 rad/s. It has been concluded that the assumption of linear variation with the basic parameters, which is a necessary prerequisite for the use of states variables analysis, is justified. The work outlined in this paper represents a step in the design process associated with the optimal control of an axial piston pump.

New Swash Plate Damping Model for Hydraulic Axial-Piston Pump

1999 ◽  
Vol 123 (3) ◽  
pp. 463-470 ◽  
Author(s):  
X. Zhang ◽  
J. Cho ◽  
S. S. Nair ◽  
N. D. Manring
Keyword(s):  
Open Loop ◽  
Operating Conditions ◽  
Reduced Order Model ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Order Model ◽  
Nonlinear Simulation ◽  
Reduced Order ◽  
Swash Plate ◽  
Axial Piston

A new, open-loop, reduced order model is proposed for the swash plate dynamics of an axial piston pump. The difference from previous reduced order models is the modeling of a damping mechanism not reported previously in the literature. An analytical expression for the damping mechanism is derived. The proposed reduced order model is validated by comparing with a complete nonlinear simulation of the pump dynamics over the entire range of operating conditions.

Surface modification effects on lubricant temperature and floating valve plate motion in an axial piston pump

2019 ◽  
Vol 234 (1) ◽  
pp. 3-17 ◽  
Author(s):  
David Richardson ◽  
Farshid Sadeghi ◽  
Richard G Rateick ◽  
Scott Rowan
Keyword(s):  
Equations Of Motion ◽  
Surface Modifications ◽  
Analytical Investigation ◽  
Operating Conditions ◽  
Valve Plate ◽  
Piston Pump ◽  
Plate Motion ◽  
Cylinder Block ◽  
Axial Piston Pump ◽  
Axial Piston

The objectives of this study were to experimentally measure motion of a floating valve plate and analytically investigate the effects of floating valve plate surface modifications on the lubricant film thickness and temperature distribution. In order to achieve the experimental objectives, a previously developed axial piston pump test rig was instrumented with proximity probes to measure the motion of the valve plate. To achieve the objectives of the analytical investigation, the thermal Reynolds equation augmented with the Jakobsson-Floberg-Olsson (JFO) boundary condition and the energy equation were simultaneously solved to determine the pressure, cavitation regions, and temperature of the lubricant at the valve plate/cylinder block interface. The lubricating pressures were then coupled with the equations of motion of the floating valve plate to develop a dynamic lubrication model. The stiffness and damping coefficients of the floating valve plate system used in the dynamic lubrication model were determined using a parametric study. The elastic deformation of the valve plate was also considered using the influence matrix approach. The experimental and analytical motions of the valve plate were then corroborated and found to be in good agreement. Four- and eight-pocket designs were then added as surface modifications to the floating valve plate in the dynamic lubrication model. The addition of surface modifications on the valve plate resulted in increased minimum film thicknesses and lowered lubricant temperatures at the same operating conditions.

Effect analysis of silencing grooves on pressure and vibration characteristics of seawater axial piston pump

2016 ◽  
Vol 231 (8) ◽  
pp. 1390-1409 ◽  
Author(s):  
Fanglong Yin ◽  
Songlin Nie ◽  
Wei Hou ◽  
Shuhan Xiao
Keyword(s):  
Three Dimensional ◽  
Vibration Characteristics ◽  
Operating Conditions ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Effect Analysis ◽  
Compressibility Effect ◽  
Low Viscosity ◽  
Dynamics Simulations ◽  
Axial Piston

Seawater axial piston pump is a critical power component in seawater fluid power system. As the properties of high bulk modulus and low viscosity of seawater, the pressure and vibration characteristics of the seawater axial piston pump will be getting poorer than the traditional oil pump. In this study, the pressure, flow, and vibration characteristics for a seawater axial piston pump are investigated. The three-dimensional computational fluid dynamics simulations for the port plate with non-grooved, U-shaped, and triangle-based pyramid silencing groove designs have been conducted over a range of operating conditions, which consider the fluid compressibility effect and cavitation damage. Measurements of pressure ripple and pump vibration are carried out at various loading conditions to verify the results of simulation. The experiment turned out that the well-designed port plate can mitigate both pressure ripples as well as vibrations of the pump. This research will lay the foundation for the further development of a low fluid noise seawater axial piston pump.

Pressure, Flow, Force, and Torque Between the Barrel and Port Plate in an Axial Piston Pump

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
J. M. Bergada ◽  
J. Watton ◽  
S. Kumar
Keyword(s):  
Pressure Distribution ◽  
Operating Conditions ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Operating Characteristics ◽  
Double Peak ◽  
Fluctuation Pattern ◽  
Total Magnitude ◽  
Axial Piston ◽  
Insight Into

This paper analyzes the pressure distribution, leakage, force, and torque between the barrel and the port plate of an axial piston pump. A detailed set of new equations is developed, which takes into account important parameters such as tilt, clearance and rotational speed, and timing groove. The pressure distribution is derived for different operating conditions, together with a complementary numerical analysis of the original differential equations, specifically written for this application and used to validate the theoretical solutions. An excellent agreement between the two approaches is shown, allowing an explicit analytical insight into barrel/port plate operating characteristics, including consideration of cavitation. The overall mean force and torques over the barrel are evaluated and show that the torque over the XX axis is much smaller than the torque over the YY axis, as deduced from other nonexplicit simulation approaches. A detailed dynamic analysis is then studied, and it is shown that the torque fluctuation over the YY axis is typically 8% of the torque total magnitude. Of particular novelty is the prediction of a double peak in each torque fluctuation resulting from the more exact modeling of the piston/port plate/timing groove pressure distribution characteristic during motion. A comparison between the temporal torque fluctuation pattern and another work shows a good qualitative agreement. Experimental and analytical results for the present study demonstrate that barrel dynamics do contain a component primarily directed by the torque dynamics.

Mathematical Modeling of a Variable Displacement Axial Piston Pump

1999 ◽  
Author(s):  
Jeff W. Dobchuk ◽  
Richard T. Burton ◽  
Peter N. Nikiforuk ◽  
Paul R. Ukrainetz
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Specific Effects ◽  
Lumped Parameter ◽  
Lumped Parameter Models ◽  
Wide Range ◽  
Variable Displacement ◽  
Axial Piston

Abstract The variable displacement axial piston pump has been the subject of much research, having been studied from the controls, noise reduction, and design perspectives. The resulting body of research is large and very diverse in content. A review of the available publications was conducted for this paper in order to identify those works that would be most helpful in developing a complete and accurate mathematical model of an axial piston pump. Most of the available publications can be classified into one of two general groups; those describing a small group of components to understand specific phenomena or those describing the entire pump for control or design purposes. The significant mathematical developments in various publications regarding specific phenomena, particularly those works involving nonlinear friction or pressure transients, were identified by the authors in this paper. When the mathematical developments of the phenomena specific effects are combined with the widely accepted kinematics equations for the pump, an accurate numerical model can be developed. Works on linearized lumped parameter models and parameter sensitivity were examined for this paper and the limitations of these types of models were addressed. While linearized models offer mathematical simplicity, they suffer from poor accuracy over a wide range of operating conditions and do not reflect instantaneous swashplate dynamics. This paper offers insight into the required complexity of a mathematical model that is necessary to achieve a desired accuracy as well as providing the appropriate references to develop that model.

The Effect of Oil Entrapment in an Axial Piston Pump

1985 ◽  
Vol 107 (4) ◽  
pp. 246-251 ◽  
Author(s):  
S. J. Lin ◽  
A. Akers ◽  
G. Zeiger
Keyword(s):  
Pressure Distribution ◽  
Dynamical Equation ◽  
Control Volume ◽  
Equation Of Motion ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Angular Rotation ◽  
Instantaneous Pressure ◽  
Discharge Pressure ◽  
Axial Piston

Values of pressure caused by entrapment beneath a valve plate have been calculated. The technique used consists of the solution of the dynamical equation of motion in the piston control volume. Instantaneous and average values of torque have also been deduced from the pressure distribution. Plots have been constructed showing the effect of swashplate angle, pump angular rotation, discharge pressure, and entrapment angle upon instantaneous pressure, torque, and average torque for a typical axial piston pump.

The Analysis of Cavitation Problems in the Axial Piston Pump

2010 ◽  
Vol 132 (7) ◽  
Author(s):  
Shu Wang
Keyword(s):  
Vapor Pressure ◽  
Control Volume ◽  
Low Pressure ◽  
Valve Plate ◽  
Piston Pump ◽  
Axial Piston Pump ◽  
Axial Piston Pumps ◽  
Design Guide ◽  
Axial Piston ◽  
Plate Geometry

This paper discusses and analyzes the control volume of a piston bore constrained by the valve plate in axial piston pumps. The vacuum within the piston bore caused by the rise volume needs to be compensated by the flow; otherwise, the low pressure may cause the cavitations and aerations. In the research, the valve plate geometry can be optimized by some analytical limitations to prevent the piston pressure below the vapor pressure. The limitations provide the design guide of the timings and overlap areas between valve plate ports and barrel kidneys to consider the cavitations and aerations.

Condition Monitoring Based on Thermodynamic Efficiency Method for an Axial Piston Pump

2018 ◽  
Author(s):  
Andrea Bedotti ◽  
Mirko Pastori ◽  
Antonio Lettini ◽  
Paolo Casoli
Keyword(s):  
Fault Detection ◽  
Operating Conditions ◽  
Piston Pump ◽  
Thermodynamic Method ◽  
Thermodynamic Efficiency ◽  
Health State ◽  
Axial Piston Pump ◽  
Flow Rates ◽  
Overall Efficiency ◽  
Axial Piston

In the last years, the interest in the field of Prognostics and Health Management (PHM) has been growing in many industrial fields. The objective of PHM is to switch from a time-based (scheduled) maintenance to a predictive maintenance with advantages in terms of reliability and safety. This paper presents the thermodynamic method for the fault detection of an axial piston pump which is a critical component in many hydraulic systems; the method was developed for the evaluation of the overall efficiency which is an important parameter to monitor the machine health state. Through the measurements of temperatures and pressures at suction and delivery ports the method allows to calculate the efficiency avoiding the use of costly sensors, such as speed and torque sensors. The paper investigates the possibility of utilizing the pump overall efficiency evaluated through the thermodynamic method as a reliable parameter for the fault detection. The machine under study is a variable displacement axial-piston pump with external drainage equipped with a load sensing regulator. The thermodynamic method was already validated in a previous work by comparing it with the standard approach, based on the direct measurement of the mechanical power. The proposed method requires the measurement of the delivery and drain flow rates involving the use of expensive flowmeters which could prevent its usage in online applications; this limit should be overcome with the development of low-cost solutions for flow rate measurements. A preliminary investigation of the pump failure modes was conducted to identify the most important faults which need to be considered. An experimental campaign was carried out on a laboratory test bench with the pump in the flawless state and in faulty states. The faulty states were realized by introducing components with artificial faults into the pump. The pump was accurately instrumented to monitor all the main variables, i.e. pressures, temperatures, flow rates, swash plate angle and shaft torque and speed. Different operating conditions were considered and each test was repeated several times in order to acquire a suitable population to verify the repeatability of the data. The experiments demonstrate the method capability of detecting some but not all of the incipient faults tested in steady-state conditions as a consequence of temperature variations which have the most important influence on efficiency estimation. Future works will include the development of innovative solutions to measure flow-rates and the testing of other faults to further verify the reliability of the method.

Influence of power fluid temperature in hydraulics on operating efficiency of hydraulic mining excavators

2020 ◽  
pp. 78-81
Author(s):  
A. E. Krivenko ◽  
◽  
Zhang Kuok Khanh ◽  
Keyword(s):  
Operating Conditions ◽  
Piston Pump ◽  
Open Pit ◽  
Fluid Temperature ◽  
Axial Piston Pump ◽  
Pump Flow ◽  
Hydraulic Mining ◽  
Hydraulic Excavators ◽  
The Republic ◽  
Axial Piston

The Republic of Vietnam has great mineral resources. Open pit mines use hydraulic excavators. In hot climate, the excavators lose capacity, and the number of the hydraulics failures grows. To identify the causes of unstable operation of the hydraulics, the authors analyze the capacity reduction factors, namely, hydraulic pump leaks. The test subject is pump HPV95 for Komatsu hydraulic excavators. The axial-piston pump leaks take place in clearances of control and injection gears, and only have mutable and cyclic behavior in the piston and cylinder clearances. This has an adverse effect on uniformity of the pump flow and on stability of the injection pressure. Generally, leaks can be evaluated from the Reynolds equation of fluid flow rate in the ring clearance. The input data are the design variables of axial-piston pump HPV95 and power fluid temperature range of Komatsu hydraulic mining excavators operated in open pit mining in the south in the Republic of Vietnam. Matlab-based Simulink modeling shows that with increasing temperature of power fluid, leaks in the injection gear grow nonlinearly in the absolute value and so does the surging amplitude in the pump flow. As a consequence, the pressure fluctuations and vibrations in the hydraulic gear elevate. The modeling also exhibits higher surge and reduced net capacity of the hydraulics with rising temperature of power fluid. These changes are caused by reduction in the flow friction in the ring channel between the piston and block of cylinders. Thus, the power fluid cooling system engineering subject to hydraulics capacity, operating conditions and cooling methods is highly critical for the efficient operation of hydraulic mining excavators.

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