Investigation Of The Pressure variation In The Chambers Of External Gear Pumps With Symmetric And Asymmetric Tooth Profiles Used In Electrohydraulic Drive Systems

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.

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The method of dynamic operating modes investigation in electrohydraulic drive systems with improved accuracy of positioning executive elements

MATEC Web of Conferences ◽

10.1051/matecconf/201822604024 ◽

2018 ◽

Vol 226 ◽

pp. 04024

Author(s):

Valeriy V. Grechikhin ◽

Galina A. Galka ◽

Anatoliy I. Ozerskiy ◽

Mikhail E. Shoshiashvili

Keyword(s):

Mutual Influence ◽

Hydraulic Drive ◽

Joint Work ◽

Operating Modes ◽

Hydraulic Machines ◽

Dynamic Operating ◽

Electrohydraulic Drive ◽

Drive Systems ◽

Improved Accuracy ◽

Executive Elements

The article describes the method of dynamic operating modes investigation in electrohydraulic drive systems with improved accuracy of positioning output element. The method is the evolution of the fundamental positions of the mechanics of continuous media with moving boundaries as applied to the research of non-stationary processes accompanying the operation of hydraulic drive systems with piston hydraulic machines. The method is based on generalized modeling (technical, physical, mathematical and computer), takes into account the peculiarities of mutual influence of electric and hydraulic machines during their joint work as part of the electrohydraulic drive, which raises the level and adequacy of actuators simulation, as well as the reliability of the assessment of their technical condition. The method extends the field of research, improves the accuracy of the calculation of the positioning of the executive elements, taking into account the different dynamic modes of the drives under study.

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Computer Prediction of Cyclic Excitation Sources for an External Gear Pump

Proceedings of the Institution of Mechanical Engineers Part B Management and engineering manufacture ◽

10.1243/pime_proc_1985_199_064_02 ◽

1985 ◽

Vol 199 (3) ◽

pp. 175-180 ◽

Cited By ~ 10

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

10.1115/fpmc2021-68605 ◽

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.

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Setup of a 1D Model for Simulating Dynamic Behaviour of External Gear Pumps

10.4271/2007-01-4228 ◽

2007 ◽

Cited By ~ 4

Author(s):

S. Falfari ◽

P. Pelloni

Keyword(s):

Dynamic Behaviour ◽

External Gear Pumps ◽

Gear Pumps ◽

1D Model

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A Design Procedure for Multistage External Gear Pumps

BATH/ASME 2020 Symposium on Fluid Power and Motion Control ◽

10.1115/fpmc2020-2797 ◽

2020 ◽

Author(s):

Davide Guerra ◽

Marco Polastri ◽

Mattia Battarra ◽

Alessio Suman ◽

Emiliano Mucchi ◽

...

Keyword(s):

Design Procedure ◽

Target Delivery ◽

Multi Stage ◽

External Gear Pumps ◽

Geometrical Features ◽

Fluid Properties ◽

Gear Pumps ◽

Working Parameters

Abstract In this work, the authors present a robust and integrated procedure for the design of multi-stage gear pumps to be used in dry sump system applications. Based on the target delivery flow rate, rotational speed and fluid properties, the developed iterative method enables to directly obtain the geometrical features and the working parameters of the pump components, such as gearpair specifics, shaft and journal bearing dimensions, clearance values. The methodology is then applied to a case study in order to highlight its features and detail the achievable outcomes. Quality of the results is assessed by means of a CFD analysis, demonstrating the capability to obtain the expected volumetric efficiency.

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Gear mesh geometry effect on performance improvement for external gear pumps

MATEC Web of Conferences ◽

10.1051/matecconf/201928701007 ◽

2019 ◽

Vol 287 ◽

pp. 01007 ◽

Cited By ~ 1

Author(s):

Viktor Ivanov ◽

Dimitar Karaivanov ◽

Svitlana Ivanova ◽

Mariia Volkova

Keyword(s):

Performance Improvement ◽

Flow Rate ◽

Bending Strength ◽

Fluid Volume ◽

Radial Clearance ◽

The Finite Element Method ◽

Gear Mesh ◽

External Gear Pumps ◽

Pump Flow Rate ◽

Gear Pumps

The parameters of the involute and cycloidal gearing which influence on fluid volume at the tooth space are analysed. It is established that to a greater extent on the flow rate of the pump with involute gearing is influenced by the radial clearance coefficient and the profile shift coefficient. The radii ratio of the auxiliary and pitch circles, as well as the radial clearance coefficient, mainly affect the flow rate of the pump with cycloidal gearing. Since the gear module is determined for reasons of pump flow rate, the teeth has a significant safety factor for contact stress and especially bending stress. This allows a wide variation of the gearing parameters in greater limits than in transmissions. The dependences of the fluid volume at the tooth space in the cycloidal gearing on the radial clearance coefficient, on the radii ratio of the auxiliary and pitch circles, on the fillet radius coefficient, is found. The boundaries of the variation of the gearing parameters were established taking into account the bending strength of the teeth. The analysis is carried out using the finite element method. Recommendations for the use of cycloidal gearing in external gear pumps have been developed.

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