Internal Combustion Engine Bearings Lubrication in Hydrodynamic Bearings

Dominique Bonneau, Aurelian Fatu, Dominique Souchet

• Publisher: Wiley-ISTE
• Year: 2014
• Print ISBN: 9781848216846
• eBook ISBN: 9781119008002
• Edition: 1
• Topic: Mathematics
• Subtopic: Mathematical Analysis
• Index: Mathematics

This Series provides the necessary elements to the development and validation of numerical prediction models for hydrodynamic bearings. This book with the specific case of internal combustion engine (ICE) journal bearing lubrication. Many examples, relating to various types of ICE, are presented.

1

Kinematics and Dynamics of Crank Shaft–Connecting Rod–Piston Linkage

In an internal combustion engine, the combination of mechanical parts, which allows the force exerted by the combustion of gas to be transformed into rotational movement resulting in vehicle wheel rotation, is referred to as “the moving part”. This includes pistons, piston pins, connecting rod bearings, connecting rods and the crank shaft. The small elements related to sealing or assembling the piston and lock rings for piston pin positioning are not discussed. Because of their low mass, these connecting elements barely influence the forces created by the moving part. The connecting rod consists of a set of assembled solid objects: connecting rod beam, cap, bearings, screws, washers and possibly nuts. It will be assumed that there is no movement between these various elements of the connecting rod.

The aim of this chapter is to determine the kinematic relationships between elements of the moving part and forces involved in the junctions. Although these elements are made up of elastic materials and are thus capable of deformation under the effect of force transmission, in this chapter they will be considered non-deformable.

The junctions between the elements of the moving part are generally made with sliding bearings. These require a lubricant film layer in order to function well. The extra hundredths of a millimeter occupied by the layer contribute to the general junction mobility and additional mobility of very small amplitudes. This notable extra mobility significantly complicates the kinematic model of the moving part.

A study on dynamics using a complete kinematic model requires knowledge of junction static and dynamic properties, e.g. all the coefficients of stiffness and damping matrices of each link, the dimensions of each matrix is equal to the degrees of freedom. The developments and examples presented in other chapters of this book show that the elastohydrodynamic behaviors of lubricated bearings in non-stationary conditions are such that they make it impossible to construct a dynamic model where the bearings would be represented by stiffness and damping matrices known in advance. Once again, the purpose of this chapter is to give the necessary background needed for junction forces calculations. A kinematic and dynamic model where the junctions are reduced to their core mobility is sufficient for acquiring results with the desired precision. In section 1.3, a model is developed that takes into account the extra mobility added by the significant deformability of the connecting rod bearing.

1.1. Kinematic model of crank shaft–connecting rod–piston linkage

1.1.1. Model description

The moving part examined is assumed to be those of a single-cylinder engine made up of five non-deformable bodies numbered from 0 to 4 as follows:

– 0: engine block;

– 1: the crank shaft with the center of rotation O and the center of mass G₁;

– 2: the connecting rod AB with the center of mass G₂;

– 3: the element coupling the connecting rod and the piston;

– 4: the piston.

The mechanism plan consists of a closed kinematic chain located in a Cartesian plane O (x₀, y₀). Only the basic mobility of the junctions between these solid bodies will be considered as follows:

– L₀₁: pivoting link between the engine block and the crank shaft with the center O and axis O z₀;

– L₁₂: pivoting link between the crank shaft and the connecting rod with...

Table of contents

• Cover
• Contents
• Title Page
• Copyright
• Preface
• Nomenclature
• 1. Kinematics and Dynamics of Crank Shaft–Connecting Rod–Piston Linkage
• 2. The Crank Shaft–Connecting Rod Link
• 3. The Connecting Rod–Piston Link
• 4. The Engine Block–Crank Shaft Link
• 5. Influence of Input Parameters and Optimization
• Index