Gear pumps represent the majority of the fixed displacement machines used for flow generation in fluid power systems. In this context, the paper presents a review of the different methodologies used in the last years for the simulation of the flow rates generated by gerotor, external gear and crescent pumps. As far as the lumped parameter models are concerned, different ways of selecting the control volumes into which the pump is split are analyzed and the main governing equations are presented. The principles and the applications of distributed models from 1D to 3D are reported. A specific section is dedicated to the methods for the evaluation of the necessary geometric quantities: analytic, numerical and Computer-Aided Design (CAD)-based. The more recent studies taking into account the influence on leakages of the interactions between the fluid and the mechanical parts are explained. Finally the models for the simulation of the fluid aeration are described. The review brings to evidence the increasing effort for improving the simulation models used for the design and the optimization of the gear machines.

Models for Flow Rate Simulation in Gear Pumps: A Review

Numerical simulation of turbulent flow in the suction chamber of a gearpump using deforming mesh and mesh replacement

In the case of internal gear pumps, the eccentricity of the outer rotor, which resembles a circular lobe, must be limited to a certain value in order to avoid the formation of cusps and loops; furthermore, the tip width of the inner rotor, which has a hypocycloid curve and an epicycloid curve, should not be allowed to exceed the limit value. In this study, we suggest that the tip width of the inner rotor be controlled by inserting a circular-arc curve between the hypocycloid and epicycloid curves. We also suggest that the outer rotor be designed using the closed-form equation for the inner rotor and the width correction coefficient. Thus, it is possible to design a gerotor for which there is no upper limit on the eccentricity, as in this case, undercut is prevented and there is no restriction on the tip width. We also develop an automated program for rotor design and calculation of the flow rate and flow rate irregularity. We demonstrate the superior performance of the gerotor developed in this study by analyzing the internal fluid flow using a commercial computational fluid dynamics (CFD)-code.

Design of Rotor for Internal Gear Pump Using Cycloid and Circular-Arc Curves

This paper explains development of the general mathematical model of trochoidal gearing that can be applied for gerotor pumps and cyclo reducers. The model analyzes geometry and physics of the gearing pair in trochoidal pump where the outer gear has one tooth more than the inner gear. The inner gear profile is described by peritrochoid equidistance and the outer gear profile by circular arc. Mathematical model of gearing with clearances is based on the principle of an ideal profile development. Minimum clearance height between teeth profiles in relation to instantaneous gear ratio is determined. The influence of gear profile geometrical parameters on gearing process, clearance height change, and pulsation of drive moment is analyzed and presented in numerical examples. Obtained results can be used for the design of the trochoidal gearing where accurate and silent operation is required. [DOI: 10.1115/1.4005621]

Modeling of the Meshing of Trochoidal Profiles With Clearances

II ACKNOWLEGEMENTS V TABLE OF CONTENTS VI LIST OF TABLES XII LIST OF FIGURES XIII LIST OF SYMBOLS XXVIII Chapter

Coupled Multi-body Dynamic and Vibration Analysis of Hypoid and Bevel Geared Rotor System

Misalignment effects on the load capacity of a hydraulic cylinder

The present paper describes an extensive study of trochoidal-gear pumps. As described in part 1 of the current paper, geometry and kinematics of trochoidal profiles and volumetric characteristics were considered to different extents. The bond graph technique was applied to model a trochoidal-gear pump based upon an ideal representation in order to simulate the instantaneous flow where the intricate aspects of leakage had been deliberately left aside. Nevertheless, leakage and interaction of the flow inside the pump are now presented in Part 2. The bond graph technique is applied to model a trochoidal-gear pump based upon a real representation in order to simulate the instantaneous flow, taking into account the different types of leakage by modelling them. Results from simulation of both models are compared and significant conclusions are obtained. The paper also examines the experimental determination of the flow ripple. A convenient method of experimentally measuring the so-called ‘secondary sour...

Flow characteristics of a trochoidal-gear pump using bond graphs and experimental measurement. Part 2:

An innovative tool for the improvement of the design methodology of a trochoidal gear, which works as a part of a hydraulic pump, is introduced. For the past few years, new, specific, and demanding applications of this type of pumps have demanded to maximize efficiency and to reduce manufacturing costs by improving its two main performance indexes: volumetric characteristics and teeth contact stress. The existing methodologies and software fail to thoroughly address the design by taking into account both performance indexes. The software presented is an integrated package system, which is composed of three basic modules: design, volumetric characteristics, and contact stress module. As a result, by consecutively following each module, this new tool allows to find the better gear set for the concrete initial required design parameters. An application using the GEROLAB package system methodology is carried out to obtain the best candidate, which is compared and contrasted with a gear set of a specific gerotor pump unit. As a conclusion, this new software aims to lead the designer to a better design by improving performance indexes of a new born gerotor pump project.

GEROLAB Package System: Innovative Tool to Design a Trochoidal-Gear Pump

The current paper presents an extensive study aimed at trochoidal-gear pumps. In recent years their important application in the automotive industry, where trochoidal-gear pumps are increas...

E. Codina

Papers

Misalignment effects on the load capacity of a hydraulic cylinder

Flow characteristics of a trochoidal-gear pump using bond graphs and experimental measurement. Part 2:

GEROLAB Package System: Innovative Tool to Design a Trochoidal-Gear Pump

Flow characteristics of a trochoidal-gear pump using bond graphs and experimental measurement. Part 1:

Analysis of the turbulence in the suction chamber of an external gear pump using Time Resolved Particle Image Velocimetry