A Design Optimization Model for an Alternating Flow (AF) Hydraulic Pump Based on First Principles

2017 ◽  
Author(s):  
Mengtang Li ◽  
Ryan Foss ◽  
Kim A. Stelson ◽  
James D. Van de Ven ◽  
Eric J. Barth
Keyword(s):  
Closed Form ◽  
Operating Conditions ◽  
Energy Output ◽  
Group Method ◽  
Displacement Control ◽  
Hydraulic Pump ◽  
Load Pressure ◽  
Wide Range ◽  
Variable Displacement ◽  
Form Model

Although current state of the art hydraulic variable displacement pumps are highly efficiently at high displacement, they have poor efficiency at low displacement. Besides, different operating speed and load pressure conditions also strongly affect their performance. This paper proposed a novel alternating flow (AF) hydraulic variable displacement pump to 1) eliminate throttling loss by acting as a high-bandwidth pump for displacement control, 2) achieve high efficiency across a wide range of operating conditions and displacements, and 3) allow multiple units to be easily common-shaft mounted for a compact multi-actuator displacement control system from a single prime-mover. This paper presents a simple closed form model for the AF hydraulic pump and shows the model validation with a first generation prototype. The simple closed form model captures input motor energy, output fluid energy and associated energy losses. With the closed form model validated, it can then be used to drive optimal design for future generation prototypes using a dimensionless group method.

Dynamic Model of a Novel Alternating Flow (AF) Hydraulic Pump

2017 ◽  
Author(s):  
Mengtang M. Li ◽  
Ryan Foss ◽  
Kim A. Stelson ◽  
James D. Van de Ven ◽  
Eric J. Barth
Keyword(s):  
Dynamic Model ◽  
High Efficiency ◽  
Check Valve ◽  
Viscous Friction ◽  
Operating Conditions ◽  
Hydraulic Systems ◽  
Displacement Control ◽  
Hydraulic Pump ◽  
Wide Range ◽  
Variable Displacement

High power density and good controllability are the most appealing characteristics that make hydraulic systems the best choice for many applications. Current state of the art hydraulic variable displacement pumps show high efficiency at high displacement while they have poor efficiencies at low displacement. This paper proposes a novel alternating flow (AF) variable displacement hydraulic pump to 1) eliminate metering losses by acting as a high-bandwidth pump for displacement control, 2) achieve high efficiency across a wide range of operating conditions and displacements, and 3) allow multiple units to be easily common-shaft mounted for a compact multi-actuator displacement control system from a single prime-mover. A dynamic model using first principles describes the cylinder pressure, flows between pairs of cylinders, and net inlet and outlet flows as a function of the pump’s phase shift angle. The model captures hydraulic check valve dynamics, the effective bulk modulus, leakage flows, and viscous friction. Piston kinematics and dynamics are discussed and energy loss models are presented and used to guide the design for a first prototype of the AF hydraulic pump. The paper presents simulation results from the model that offer an initial evaluation of this novel pump concept and potential applications.

Investigation of Instability of a Pressure Compensated Vane Pump

2016 ◽  
Author(s):  
Ryan P. Jenkins ◽  
Monika Ivantysynova
Keyword(s):  
Control Volume ◽  
Operating Conditions ◽  
Working Fluid ◽  
Displacement Control ◽  
Vane Pump ◽  
Flow Rates ◽  
Wide Range ◽  
Oil Flow ◽  
Variable Displacement ◽  
Cooling And Lubrication

Currently, fixed displacement pumps are typically used to provide the oil flow required for actuation of the clutches, cooling, and lubrication of automatic transmissions. This results in significant power losses as excess flow at higher engine speeds is throttled through orifices back to the tank. Therefore, the use of variable displacement pumps to supply the required oil flow can reduce the overall fuel consumption of the vehicle by eliminating this excess flow at high engine speeds. This paper presents the development and experimental validation setup of a model for a pressure compensated pivoting-cam-type variable displacement vane pump (VDVP) that is suitable for these applications. The pump operates at low system pressures (typically ∼5 bar with maximum 20 bar) with significant amounts of entrained air present in the working fluid (typically 3% by volume at the delivery) over a wide range of input speeds (700–6000 rpm). These conditions, along with a combination of a highly dynamic flow demand and dynamically changing pressure compensation setting, result in pump instabilities and loss of controllability. Previously, high leakage flow rates were introduced into the cam displacement control volume in an attempt to stabilize the pump with limited improvements. A high fidelity simulation model of the VDVP displacement chambers and cam displacement control volume pressure development was created in MATLAB/Simulink to accurately predict pump flow rates and cam dynamics in order to investigate these instabilities and methods for increasing the controllability of the VDVP. Additionally, the model provides a platform to assess the system sensitivity to changes in fluid/air mixture ratio, vane spacing, bias spring rate, and pump outlet pressure. A modified pump that was instrumented to measure the pressure gradients within each displacement chamber at the transitions between the suction and delivery ports under realistic operating conditions is presented. The modified pump was also instrumented with a linear variable displacement transducer (LVDT) to directly measure cam position during pump operation on an experimental test bed incorporating actual control valves found in an automatic transmission.

Design and Testing of an Adjustable Linkage for a Variable Displacement Pump

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
Shawn R. Wilhelm ◽  
James D. Van de Ven
Keyword(s):  
High Efficiency ◽  
Operating Conditions ◽  
The Novel ◽  
Hydraulic Pump ◽  
Low Friction ◽  
Transmission Angle ◽  
Displacement Pump ◽  
Order Of Magnitude ◽  
Variable Displacement ◽  
Design And Testing

A variable displacement hydraulic pump/motor with high efficiency at all operating conditions, including low displacement, is beneficial to multiple applications. Two major energy loss terms in conventional pumps are the friction and lubrication leakage in the kinematic joints. This paper presents the synthesis, analysis, and experimental validation of a variable displacement sixbar crank-rocker-slider mechanism that uses low friction pin joints instead of planar joints as seen in conventional variable pump/motor architectures. The novel linkage reaches true zero displacement with a constant top dead center position, further minimizing compressibility energy losses. The synthesis technique develops the range of motion for the base fourbar crank-rocker and creates a method of synthesizing the output slider dyad. It is shown that the mechanism can be optimized for minimum footprint and maximum stroke with a minimum base fourbar transmission angle of 30 deg and a resultant slider transmission angle of 52 deg. The synthesized linkage has a dimensionless stroke of 2.1 crank lengths with a variable timing ratio and velocity and acceleration profiles in the same order of magnitude as a comparable crank-slider mechanism. The kinematic and kinetic results from an experimental prototype linkage agree well with the model predictions.

scholarly journals Closed form Models for Pull-In Voltage of Electrostatically Actuated Cantilever Beams and Comparative Analysis of Cantilevers and Microgripper

2012 ◽  
Vol 63 (4) ◽  
pp. 242-248 ◽  
Author(s):  
Kalaiarasi Ramakrishnan ◽  
Hosimin Srinivasan
Keyword(s):  
Comparative Analysis ◽  
Closed Form ◽  
Maximum Deviation ◽  
Cantilever Beams ◽  
Mems Devices ◽  
Element Analysis ◽  
3D Finite Element ◽  
Electrostatically Actuated ◽  
Wide Range ◽  
Form Model

Closed form Models for Pull-In Voltage of Electrostatically Actuated Cantilever Beams and Comparative Analysis of Cantilevers and MicrogripperPull-in voltage Evaluation is significant for the design of electrostatically actuated MEMS devices. In this work simple closed form models are derived for computation of pull-in voltage of cantilever beams. These models are obtained based on five different capacitance models suitable for wide range of dimensions. Using these models pull-in voltages are computed for a range of dimensions and the results are compared with the experimentally verified 3D finite element analysis results. The results show that, for every given range of dimension, choice of the model changes for the evaluation of the pull-in voltage with a maximum deviation of 2%. Therefore for a given range of dimension appropriate closed form model is to be chosen for accurate computation of pull-in voltage. Computation of pull-in voltage of microgripper further validates the closed form models. The results again show that for a given range of dimension only a particular model evaluates the pull-in voltage with less error.

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.

Efficiency Testing of an Adjustable Linkage Triplex Pump

2014 ◽  
Author(s):  
Shawn R. Wilhelm ◽  
James D. Van De Ven
Keyword(s):  
Second Generation ◽  
High Efficiency ◽  
Mechanical Efficiency ◽  
Operating Conditions ◽  
Hydraulic Systems ◽  
Wide Range ◽  
Potential Applications ◽  
Work Input ◽  
Variable Displacement ◽  
Pressure Ripple

Current state of the art variable displacement pumps suffer from poor efficiency at low volumetric displacement. Additionally, their performance is strongly dependent on operating conditions. A new variable displacement linkage pump architecture has been developed which can achieve high efficiency across a wide range of operating conditions. Previous work has described the kinematics, energy loss modeling, and experimental validation of a low power single cylinder prototype as well as the design of a second generation prototype. The second generation pump employs roller element bearings in its joints to minimize friction losses and the three cylinder design reduces the pressure ripple. In this paper, experimental characterization is presented of the new 21 MPa, 6.75 cc/rev pump. High mechanical efficiency is achieved at low volumetric displacements at partial loads as low as 0.6% of maximum power. Poorly performing cartridge check valves result in low volumetric efficiencies at low displacements. Close agreement was obtained between the model and predicted work input using measured cylinder data as an input into the model. This work shows that the presented pump with properly functioning valves can achieve high efficiency across a wide range of operating conditions. Having such versatile pump performance can greatly improve the performance of hydraulic systems as well as expand their potential applications.

Analysis of the steady-state performance of a multi-plunger hydraulic pump

2002 ◽  
Vol 216 (6) ◽  
pp. 471-479 ◽  
Author(s):  
K Dasgupta ◽  
S K Mondal
Keyword(s):  
Steady State ◽  
Standard Procedure ◽  
Operating Conditions ◽  
Low Flow ◽  
Hydraulic Pump ◽  
Chamber Volume ◽  
Wide Range ◽  
Loss Coefficients ◽  
Structured Approach ◽  
Steady State Performance

In this article the steady-state performance of a multi-plunger low-flow high-pressure hydraulic pump has been studied. The variation of the chamber volume with shaft rotation, along with the various flow and torque losses, demands a structured approach to arrive at its mathematical model. A bondgraph simulation technique has been used to model the system, where various losses are lumped in suitable resistive elements. Using the standard procedure, experiments have been conducted for a wide range of operating conditions. The trends of the various loss coefficients are identified. The performance of the pump has been experimentally verified.

Comparison of Deterministic and Linear Cosine Spatial Filtering of Transmission Electron Micrographs

1972 ◽  
Vol 30 ◽  
pp. 596-597
Author(s):  
David A. Ansley
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Spatial Filter ◽  
Operating Conditions ◽  
Objective Lens ◽  
List Type ◽  
Spatial Filters ◽  
Transmission Electron ◽  
Wide Range

The coherence of the electron flux of a transmission electron microscope (TEM) limits the direct application of deconvolution techniques which have been used successfully on unmanned spacecraft programs. The theory assumes noncoherent illumination. Deconvolution of a TEM micrograph will, therefore, in general produce spurious detail rather than improved resolution.A primary goal of our research is to study the performance of several types of linear spatial filters as a function of specimen contrast, phase, and coherence. We have, therefore, developed a one-dimensional analysis and plotting program to simulate a wide 'range of operating conditions of the TEM, including adjustment of the:(1) Specimen amplitude, phase, and separation(2) Illumination wavelength, half-angle, and tilt(3) Objective lens focal length and aperture width(4) Spherical aberration, defocus, and chromatic aberration focus shift(5) Detector gamma, additive, and multiplicative noise constants(6) Type of spatial filter: linear cosine, linear sine, or deterministic

Truck Tire Operating Temperatures on Flat and Curved Test Surfaces

2005 ◽  
Vol 33 (3) ◽  
pp. 156-178 ◽  
Author(s):  
T. J. LaClair ◽  
C. Zarak
Keyword(s):  
Flat Surface ◽  
Operating Temperature ◽  
Operating Conditions ◽  
Load Pressure ◽  
Truck Tire ◽  
Endurance Testing ◽  
Operating Temperatures ◽  
The Impact ◽  
Tread Rubber ◽  
Cylindrical Test

Abstract Operating temperature is critical to the endurance life of a tire. Fundamental differences between operations of a tire on a flat surface, as experienced in normal highway use, and on a cylindrical test drum may result in a substantially higher tire temperature in the latter case. Nonetheless, cylindrical road wheels are widely used in the industry for tire endurance testing. This paper discusses the important effects of surface curvature on truck tire endurance testing and highlights the impact that curvature has on tire operating temperature. Temperature measurements made during testing on flat and curved surfaces under a range of load, pressure and speed conditions are presented. New tires and re-treaded tires of the same casing construction were evaluated to determine the effect that the tread rubber and pattern have on operating temperatures on the flat and curved test surfaces. The results of this study are used to suggest conditions on a road wheel that provide highway-equivalent operating conditions for truck tire endurance testing.

Structure and properties of compact articles from high-alloyed iron powder with adding of boron nitride

2020 ◽  
pp. 39-48
Author(s):  
B. O. Bolshakov ◽  
◽  
R. F. Galiakbarov ◽  
A. M. Smyslov ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Boron Nitride ◽  
Grain Boundary ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Operating Conditions ◽  
Structure And Properties ◽  
Steam Turbines ◽  
Friction Forces ◽  
Wide Range

The results of the research of structure and properties of a composite compact from 13 Cr – 2 Мо and BN powders depending on the concentration of boron nitride are provided. It is shown that adding boron nitride in an amount of more than 2% by weight of the charge mixture leads to the formation of extended grain boundary porosity and finely dispersed BN layers in the structure, which provides a high level of wearing properties of the material. The effect of boron nitride concentration on physical and mechanical properties is determined. It was found that the introduction of a small amount of BN (up to 2 % by weight) into the compacts leads to an increase in plasticity, bending strength, and toughness by reducing the friction forces between the metal powder particles during pressing and a more complete grain boundary diffusion process during sintering. The formation of a regulated structure-phase composition of powder compacts of 13 Cr – 2 Mо – BN when the content of boron nitride changes in them allows us to provide the specified physical and mechanical properties in a wide range. The obtained results of studies of the physical and mechanical characteristics of the developed material allow us to reasonably choose the necessary composition of the powder compact for sealing structures of the flow part of steam turbines, depending on their operating conditions.

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