An Analysis of the Effects Causing an Asymmetric Behavior of the Lateral Lubricating Films of External Spur Gear Machines

2021 ◽  
Author(s):  
Kaeul Lim ◽  
Federico Zappaterra ◽  
Swarnava Mukherjee ◽  
Andrea Vacca
Keyword(s):  
Spur Gear ◽  
Common Assumption ◽  
Simulation Tools ◽  
Positive Displacement ◽  
Asymmetric Behavior ◽  
External Gear Pumps ◽  
Pressure Development ◽  
Gear Pumps ◽  
Set Up ◽  
Lateral Gaps

Abstract The torque efficiency and flow efficiency of positive displacement machines for fluid power applications are determined by the behavior of their internal lubricating interfaces. This aspect has motivated the development of tribological simulation tools for the analysis of these interfaces. The level of details these tools can provide allows explaining some counterintuitive aspects that occur in these interfaces. This paper focuses on a significant example, which is the high asymmetric behavior of the lubricating films occurring in pressure compensated external gear pumps. These units are often designed with a symmetric axial balancing compensation system. Notwithstanding, there are differences between the lateral gaps that can be explained only considering the mutual effects of the pressure development in the film and the material deformation. To study this problem, this paper utilizes the tool Multics-HYGESim developed by the authors’ research team. Two analyses are performed: the first one imposing axial symmetry in the behavior of the gap, which is the common assumption discussed in literature; the second one (referred to as “full configuration”), which holds the asymmetric behavior of the gap. An experimental set-up is used to validate the modeling assumptions based on the measurements of the drain leakage and volumetric efficiency. The main paper findings are on the uneven distribution of these leakages, which indicates an asymmetric behavior of the gap films in the unit.

Design and Performance of a Curvilinear Circular-Arc Tooth Gear for Gear Pump Applications

2020 ◽  
Author(s):  
Logan T. Williams
Keyword(s):  
Spur Gear ◽  
Sound Level ◽  
Tooth Profile ◽  
Gear Pump ◽  
Gear Design ◽  
External Gear Pumps ◽  
Tooth Gear ◽  
Gear Pumps ◽  
Axial Profile ◽  
And Performance

Abstract The most common gear architecture used in external gear pumps is the spur gear with an involute tooth profile. The involute spur gear has many benefits, such as a constant line of action, tolerance to parallel misalignment, and ease of fabrication. However, the involute spur gear has two major drawbacks in pump applications: the tooth profile results in trapped pockets of fluid that contribute to pressure spikes and noise generation, and the straight axial profile further increases noise due to intermittent tooth shock during meshing. Current state-of-the-art pumps utilize helical gears to enable a gradual mesh to reduce noise and pressure pulsation, which results in an axial load induced on the gears during meshing. A novel gear design has been developed that eliminates axial gear loading while preserving a gradual mesh. A hybrid tooth profile eliminates the trapped fluid pocket while maintaining the benefits of an involute profile. Initial testing demonstrates an increase in volumetric efficiency by 10% and a reduction of sound level by 7 dB compared to a spur gear of the same size.

A Model-Based Comparative Investigation on the Noise Source of Hydraulic Gear Pumps

2017 ◽  
Author(s):  
Sangbeom Woo ◽  
Xinran Zhao ◽  
Andrea Vacca ◽  
Manuel Rigosi
Keyword(s):  
Noise Source ◽  
Spur Gear ◽  
Comparative Investigation ◽  
Noise Emission ◽  
Virtual Design ◽  
Noise Sources ◽  
External Gear Pumps ◽  
Noise Transmission ◽  
Airborne Noise ◽  
Gear Pumps

The reduction of the noise emission level of hydraulic pumps has been a primary research goal in the fluid power field for decades. To pursue this goal, a significant effort has been put in identifying the sources of noise generation, and formulating proper methods to reduce them. Most common methods include the analysis of the kinematic features of the displacing action realized by the unit, and/or the pressure fluctuation at the pump ports. However, the physical complexity associated with the noise transmission into the pump structure and the surrounding environment has not permitted so far to achieve clear correlations between fluid-borne noise sources and actual emitted noise. Recently, the advancement in numerical acoustic modelling techniques has permitted to explore these features, so that in future, quieter units could be designed with the help from simulation. This paper contributes in this topic, considering as a particular reference unit, the case of external gear pumps. An acoustic model developed by the authors’ research group permits to perform analysis of both structure- and air-borne noise, by combining a modal analysis performed in ANSYS and an acoustic simulation in LMS.Virtual.Lab. As pressure and force loading inputs, the model utilizes the results of the authors’ HYGESim tool. To show the model’s potentials, the paper takes into considerations two alternative gear designs suitable for the same pump casing: one single flank and one dual flank (zero-backlash). The dual-flank design is commonly considered as a quieter solution for spur gear pumps. These designs are properly selected to show differences in fluid-borne noise source, and describes the features of the noise transmission as predicted by the model. By showing the simulated level of airborne noise for the two considered designs, the results of this paper confirm the advantages of the dual-flank solution, and point out how the proposed model can be used in future for virtual design purposes.

scholarly journals Theoretical Investigation into the Ripple Source of External Gear Pumps

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 535 ◽  
Author(s):  
Xinran Zhao ◽  
Andrea Vacca
Keyword(s):  
Fluid Power ◽  
Flow Pulsation ◽  
Positive Displacement ◽  
System A ◽  
Novel Approach ◽  
Lumped Parameter ◽  
External Gear Pumps ◽  
Gear Pumps ◽  
Increasing Demand ◽  
Good Interpretation

External gear pumps are among the most popular fluid power positive displacement pumps, however they often suffer of excessive flow pulsation transmitted to the downstream circuit. To meet the increasing demand of quiet operation for modern fluid power system, a better understanding of the ripple source of gear pumps is desirable. This paper presents a novel approach for the analysis of the ripple source of gear pumps based on decomposition into a kinematic component and a pressurization component. The pump ripple can be regarded as the superposition of the displacement solution and the pressurization solution. The displacement solution is driven by the kinematic flow, and it can be derived from the kinematic flow theory; instead, the pressurization solution can be approximated by overlapping the pressurization flow for a single displacement chamber. Furthermore, in this way the changes of these two components with modification of the delivery circuit are determined in both analytical and numerical ways. The result of this analysis provides a good interpretation of the pulsation simulated by a detailed lumped-parameter simulation model, thus showing its validity. The result also indicates that the response of two ripple sources to the change of the loading in the downstream hydraulic circuit is very different. These findings reveal the limitation of the traditional experimental method for determining the pump ripple, that new experimental methods which are more physics-based can be potentially formulated based on this work.

An Optimization Approach to the Displacement Volumes for External Spur Gear Pumps

2008 ◽  
Vol 594 ◽  
pp. 57-71 ◽  
Author(s):  
Kuo Jao Huang ◽  
Wen Ruey Chang ◽  
Wun Chuan Lian
Keyword(s):  
Optimal Design ◽  
Spur Gear ◽  
Design Parameters ◽  
Optimization Approach ◽  
Spur Gears ◽  
Optimization Analysis ◽  
External Gear Pumps ◽  
Design And Manufacturing ◽  
Gear Pumps ◽  
Involute Curve

To increase volume displacement is always concerning in designing external gear pumps (EGPs). Therefore, an approach of optimization analysis intending to enhance their displacement capability is proposed in this study. Through that, design parameters of the spur gears in the pumps are systematically resulted to achieve their optimal volume displacements. Parametrically, a CAD model to visualize the designed gear of the optimal design is also created. Firstly, the study derives tooth profile equations by using the coordinate transformation and equation of meshing for gears on a rack cutter profile. Then, an analytic formula represented the enveloping area by an involute curve is derived. Next, volumes of output and trapped backflow of the EGP are achieved. Therefore the net output volume can be calculated accurately and efficiently. After that, the optimization analysis to maximize the volume displacement is performed. Through that, optimal design parameters for the pumps are achieved under assigned constraints for considerations of design and manufacturing. Additionally, influences of module, pressure angle, and addendum correction factor for the gears in the pumps on their displacement capability are also investigated. Additionally, flowrate fluctuation characteristics under different pressure angles of gears are finally discussed.

Design, Modeling and Analysis of a Gear Pump for Dispensing Application

2014 ◽  
Vol 592-594 ◽  
pp. 1035-1039 ◽  
Author(s):  
R. Hemanth
Keyword(s):  
Volume Flow Rate ◽  
Gear Pump ◽  
Modeling And Analysis ◽  
Positive Displacement ◽  
Critical Areas ◽  
External Gear Pumps ◽  
High Fructose ◽  
Gear Pumps ◽  
Available Technology ◽  
The Cost

Gear pumps are the most efficient positive displacement pumps that are being used in very high precision metering application and also with the cost of production of these pumps almost cut by a 25% to the conventional pumps, the external gear pumps have been a clear choice for the dispensing application in various industries. The design and modelling the concepts have been formulated using SOLIDWORKS modelling software and pump is aimed at delivering 20 bar of high fructose sugar syrup which will yield the required volume flow rate. Available technology was utilized in the design and fabrication of the external gear pump.[1] The design considerations and the relevant theories will affect the performance of the pump. The major factor in the pump being the nozzles that are being changed and what are the critical areas have validated using ABAQUS software.

scholarly journals Theoretical and Experimental Fatigue Strength Calculations of Lips Compensating Circumferential Backlash in Gear Pumps

Energies ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 251
Author(s):  
Piotr Osiński ◽  
Grzegorz Chruścielski ◽  
Leszek Korusiewicz
Keyword(s):  
Maximum Stress ◽  
Theoretical Calculations ◽  
Fatigue Loading ◽  
Minimum Thickness ◽  
Bending Tests ◽  
External Gear Pumps ◽  
Gear Pumps ◽  
In Series ◽  
Number Of Cycles ◽  
Technical Solutions

This article presents theoretical and experimental calculations of the minimum thickness of a compensation lip used in external gear pumps. Pumps of this type are innovative technical solutions in which circumferential backlash (clearance) compensation is used to improve their volumetric and overall efficiency. However, constructing a prototype of such a pump requires long-lasting research, and the compensation lip is its key object, due to the fact that it is an element influenced by a notch and that it operates in unfavorable conditions of strong fatigue stresses. The theoretical calculations presented in this article are based on identifying maximum stress values in a fatigue cycle and on implementing the stress failure condition and the conditions related to the required value of the fatigue safety factor. The experimental research focuses on static bending tests of the lips as well as on the fatigue loading of the lips in series of tests at increasing stress values until lip failure due to fatigue. The tests allowed the minimum lip thickness to be found for the assumed number of fatigue cycles, which is 2.5 times the number of cycles used in wear margin tests.

scholarly journals Adverse Selection, Heterogeneous Beliefs, and Evolutionary Learning

2021 ◽  
Author(s):  
Clemens Buchen ◽  
Alberto Palermo
Keyword(s):  
Adverse Selection ◽  
Relative Size ◽  
Nonlinear Dynamic System ◽  
Heterogeneous Beliefs ◽  
Evolutionary Learning ◽  
Common Assumption ◽  
Cobweb Model ◽  
The Common ◽  
Learning Set ◽  
Set Up

AbstractWe relax the common assumption of homogeneous beliefs in principal-agent relationships with adverse selection. Principals are competitors in the product market and write contracts also on the base of an expected aggregate. The model is a version of a cobweb model. In an evolutionary learning set-up, which is imitative, principals can have different beliefs about the distribution of agents’ types in the population. The resulting nonlinear dynamic system is studied. Convergence to a uniform belief depends on the relative size of the bias in beliefs.

Computer Prediction of Cyclic Excitation Sources for an External Gear Pump

1985 ◽  
Vol 199 (3) ◽  
pp. 175-180 ◽  
Author(s):  
K Foster ◽  
R Taylor ◽  
I M Bidhendi
Keyword(s):  
Computer Program ◽  
Gear Pump ◽  
Computer Prediction ◽  
Pressure Distributions ◽  
External Gear Pumps ◽  
Theoretical Predictions ◽  
Gear Pumps ◽  
External Gear Pump

A description is given of a computer program for investigating the performance of the external gear pumps under varying conditions with the special emphasis on the examination of pressure distributions within the pump, i.e. excitation forces for the vibration of the pump case and the variation in flow generated by the pump. Measurements are presented for the variation with time of tooth space pressure and the results are compared with the theoretical predictions from the computer program.

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