An Approach to Visualize Lifetime Limiting Factors in the Cylinder Block/Valve Plate Gap in Axial Piston Pumps

2017 ◽  
Author(s):  
Roman Ivantysyn ◽  
Ahmed Shorbagy ◽  
Jürgen Weber
Keyword(s):  
State Of The Art ◽  
Operating Conditions ◽  
Valve Plate ◽  
Limiting Factors ◽  
Cylinder Block ◽  
Axial Piston Pumps ◽  
First Results ◽  
Gap Height ◽  
Axial Piston ◽  
External Loads

The lifetime of axial piston pumps is depending on the application and it’s overall robustness to external loads, but even in ideal conditions pumps will fail eventually. The analytics to this problem are known to pump manufacturers. Bearing and shaft calculations paired with FEM models are invaluable tools, however the main questions remain with the rotating kit – cylinder block, pistons, and slippers. If properly designed these parts should theoretically outlast the finite lifetime parts, such as roller bearings due to their hydrostatic and hydrodynamic bearings. In reality however failures still occur due to fatigue or other factors such as contamination or wear. This paper describes an approach for the thermal analysis of the cylinder block / valve plate sealing interface. Using a state of the art test rig the temperature distribution, instantaneous gap height as well as particle wear have been analyzed across the entire operating range of an axial piston pump at the block / valve plate sealing interface. Simulations are done with cooperation of Purdue University by using their developed gap simulation model called Caspar FSTI. These simulations along with the measurements are used to locate potential lifetime reducing operating conditions and analyze them. The first results of the thermal behavior of this interface will be presented in this paper.

“Transparent Pump”: An Approach to Visualize Lifetime Limiting Factors in Axial Piston Pumps

2016 ◽  
Author(s):  
Roman Ivantysyn ◽  
Jürgen Weber
Keyword(s):  
Pressure Sensors ◽  
Transitional Zone ◽  
Operating Conditions ◽  
Valve Plate ◽  
Limiting Factors ◽  
Cylinder Block ◽  
Axial Piston Pumps ◽  
Critical Areas ◽  
First Results ◽  
Axial Piston

The lifetime of axial piston pumps is depending on the application and it’s overall robustness to external loads, but even in ideal conditions pumps will fail eventually. The analytics to this problem are known to pump manufacturers. Bearing and shaft calculations paired with FEM models are invaluable tools, however the main questions remain with the rotating kit — cylinder block, piston, and slippers. If properly designed these parts should theoretically outlast the finite lifetime parts, such as roller bearings due to their hydrostatic and hydrodynamic bearings. In reality however failures still occur due to fatigue or other factors such as contamination or wear. This paper describes the approach to measure and quantify the physical effects that occur in the lubricating gaps of axial pumps by means of simulation and measurements. Simulations are done with cooperation of Purdue University and the Caspar FSTI tool. These simulations are used to locate potential lifetime affecting areas and analyze them. The analysis includes temperature and pressure distributions in the gap with changing operating conditions and studies of the influence of wear and deformation on the parts that are forming the lubricating gaps. After the most critical areas are located within the simulation environment, gap and temperature sensors are placed right at these critical locations. This is planned at two of the three main lubricating gaps — slipper and swash plate as well as cylinder block and valve plate. In addition pressure sensors are placed within many critical areas of the pump, such as the transitional zone between high pressure and low pressure on the valve plate, as well as in the displacement chamber. The first results for the slipper/swashplate investigation of this approach will be shown in this paper.

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.

Experimental Investigation of the Cylinder Block Movement in an Axial Piston Machine

2015 ◽  
Author(s):  
Stephan Wegner ◽  
Stefan Gels ◽  
Dal Sik Jang ◽  
Hubertus Murrenhoff
Keyword(s):  
Viscous Friction ◽  
Friction Torque ◽  
Operating Conditions ◽  
Valve Plate ◽  
Measuring System ◽  
Cylinder Block ◽  
Experimental Investigations ◽  
German Research Foundation ◽  
Block Movement ◽  
Axial Piston

The greatest share of hydromechanic and volumetric losses in axial piston machines are produced within the tribological interfaces piston / cylinder, cylinder block / valve plate and slipper / swash plate. Hydrostatic and hydrodynamic effects are used to minimise the sum of solid friction, viscous friction and throttle losses. Other tribological interfaces have minor influence on efficiency losses in most operating points in machines of this type. This paper focuses on experimental investigations with the objective to acquire further knowledge on the cylinder block / valve plate contact. The investigations are part of a project funded by the German Research Foundation in which experimental and simulative investigations are combined to identify the effects influencing this tribological interface. The experiments focus on the multi-directional movement of the cylinder block and the friction torque within the contact. Therefore a test rig was built, capable of measuring the cylinder block movement in all degrees of freedom and the friction torque between both parts. A sensor system is built around a standard rotary group of an axial piston pump with a spherical cylinder block / valve plate contact. The pump functionality is maintained and measurements under standard operating conditions up to 30 MPa are possible. Procedures of the design process and descriptions of the measuring system are presented, followed by results of the cylinder block movement measurement, comparing the behavior under different pressure levels and speeds.

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.

scholarly journals A new dynamic seven-stage model for thickness prediction of the film between valve plate and cylinder block in axial piston pumps

2016 ◽  
Vol 8 (9) ◽  
pp. 168781401667144 ◽  
Author(s):  
Chao Zhang ◽  
Shaokang Huang ◽  
Jun Du ◽  
Xingjian Wang ◽  
Shaoping Wang ◽  
...  
Keyword(s):  
Valve Plate ◽  
Cylinder Block ◽  
Stage Model ◽  
Axial Piston Pumps ◽  
Thickness Prediction ◽  
Axial Piston

A partial lubrication model between valve plate and cylinder block in axial piston pumps

2015 ◽  
Vol 229 (17) ◽  
pp. 3201-3217 ◽  
Author(s):  
Lei Han ◽  
Shaoping Wang ◽  
Chao Zhang
Keyword(s):  
Film Thickness ◽  
Reynolds Equation ◽  
Multiple Scales ◽  
Valve Plate ◽  
Cylinder Block ◽  
Height Distribution ◽  
Axial Piston Pumps ◽  
Surface Profiles ◽  
Axial Piston ◽  
Lubrication Conditions

Axial piston hydraulic pumps are commonly used in aircraft, which makes analysis of their lubrication conditions of significant importance. Oil film between valve plate and cylinder block plays an most important role in pump lubrication. This paper proposes a partial lubrication model of the contact surfaces between valve plate and cylinder block in axial piston pumps for predicting film thickness. The asperity curvature at multiple scales and height distribution are obtained by analyzing actual contact surface profiles, then the separating pressure of asperities is estimated by the Hertz theory and the fluid separating pressure is calculated by Reynolds equation. Experimental results indicate that this model can predict film thickness accurately.

scholarly journals Characteristics of Fluid Films Between a Valve Plate and a Cylinder Block of Axial Piston Pumps and Motors

1984 ◽  
Vol 15 (4) ◽  
pp. 314-321 ◽  
Author(s):  
Atushi Yamaguchi ◽  
Yasuo Fujitani ◽  
Yukio Isoda ◽  
Seiji Shimizu
Keyword(s):  
Valve Plate ◽  
Cylinder Block ◽  
Fluid Films ◽  
Axial Piston Pumps ◽  
Axial Piston
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