Design of a Hydraulic Variable Compression Ratio Piston for a Heavy Duty Internal Combustion Engine Thesis by Sultan Mubarak Al Mudraa In Partial Fulfillment of the Requirements For the Degree of Master of Science King Abdullah University of Science and Technology Thuwal, Kingdom of Saudi Arabia July, 2018 2 EXAMINATION COMMITTEE The thesis of Sultan Al Mudraa is approved by the examination committee. Committee Chairperson: Prof. Bengt Johansson Committee Members: Prof. Sigurdur Thoroddsen, Prof. Omar Knio 3 Copyright © July, 2018 Sultan Al Mudraa All Rights Reserved 4 ABSTRACT Design of a Hydraulic Variable Compression Ratio Piston for a Heavy Duty Internal Combustion Engine Sultan Mubarak Al Mudraa A High percentage of fuel consumption worldwide is in internal combustion engines which has led environmental organizations and authorities to put further pressure on the engine industries to reduce CO2 emissions and enhance engine efficiency. However, historically, the effect of the compression ratio on increasing thermal efficiency of the engine is well known, hence; numerous technical solutions have been proposed to implement a variable compression ratio concept. A new first-class engineering solution to use a hydraulic piston was initially patented by BICERA (British Internal Combustion Engine Research Association) , then improved by Continental and Daimler Benz. A Hydraulic variable compression ratio piston is a hydraulically actuated piston that provides a practical method of obtaining a variable compression ratio piston. In this literature, a hydraulic variable compression ratio piston for a Volvo D13 diesel engine was designed, analyzed, modeled and discussed. This analysis was accomplished by first performing kinematic and dynamic analyses for the piston motion and acceleration based on the crank-slider mechanism. Following this the oil flow characteristics were defined in every mechanical element transferring the oil in its journey from the engine pump to the piston. Moreover, two different designs were proposed in an attempt to predict the compression ratio by modeling the hydraulic, dynamic and engine execution simultaneously. Additionally, stress on the piston was analyzed using Finite Element Analysis (FEA) to assure piston sustainment and rigidity against the harsh combustion chamber environment. In conclusion, the best design was successfully selected and finalized to reach a wide compression ratio range under a boosted inlet pressure based on the selected design, dimensions, check valves and relief valves. 5 ACKNOWLEDGMENTS This work would never have been possible without foremost help, blessing, and mercy from Allah. All Praise be to him, the one who taught by the pen and taught humans what they did not know. Secondly, I would like to express my sincere and honest thankfulness to my advisor, Prof. Bengt Johansson who gave me the opportunity to work on such a great advanced technology and design project. Thanks also to my colleague, Hao Shi, who participated with me in this project and has made a great contribution to this work. He is a great and smart candidate I was glad to work with. I would also like to extend my deep gratitude, thankfulness and love to my great family and particularly my parents and my wife for their ultimate support and continuous encouragement. 6 TABLE OF CONTENTS EXAMINATION COMMITTEE .................................................................................... 2 Copyright ........................................................................................................................... 3 ABSTRACT ....................................................................................................................... 4 ACKNOWLEDGMENTS ................................................................................................ 5 TABLE OF CONTENTS ................................................................................................. 6 LIST OF ABBREVIATIONS .......................................................................................... 8 NOMENCLATURE .......................................................................................................... 9 LIST OF ILLUSTRATIONS ......................................................................................... 11 LIST OF TABLES .......................................................................................................... 14 Chapter 1 Introduction................................................................................................... 15 1.1 Motivation and Objectives.......................................................................................... 15 1.2 Background and Previous VCR Technical Solutions .............................................. 19 1.2.1 Moving Cylinder Head ................................................................................................. 20 1.2.2 Changing Volume of the Combustion Chamber .......................................................... 21 1.2.3 Varying Connecting Rod Geometry ............................................................................. 22 1.2.4 Moving the Pin of the Crank Shaft: .............................................................................. 23 1.2.5 Dual Piston Mechanism ............................................................................................... 24 1.2.6 Brevick Pressure Reactive Piston: ................................................................................ 25 1.3 VCR with Hydraulic Piston Technology ................................................................... 26 1.3.1 Basic Principle of BICERA Piston ............................................................................... 26 1.3.2 Mode of Operation ....................................................................................................... 28 1.3.3 BICERA Mk llc ............................................................................................................ 32 1.3.4 Continental Hydraulic Piston ....................................................................................... 34 1.3.5 Daimler Benz Hydraulic Piston .................................................................................... 37 1.3.6 Measurement and Hydraulic Control Element used Daimler Benz Hydraulic Piston .. 39 1.3.7 Limitation and Challenges of Hydraulic VCR Piston .................................................. 41 1.4 Aim of this thesis ......................................................................................................... 42 1.5 Engine Setup ................................................................................................................ 43 Chapter 2 Kinematics and Dynamic of Engine Piston ................................................ 44 2.1 Piston Kinematics ........................................................................................................ 44 2.2 Piston Dynamics .......................................................................................................... 48 2.2.1 Gas Forces: ................................................................................................................... 48 2.2.2 Mass Forces .................................................................................................................. 50 2.2.3 Results for Engine Forces ............................................................................................. 51 Chapter 3 Hydraulic Oil Analysis ................................................................................. 52 3.1 Oil Path ........................................................................................................................ 52 3.2 Engine Pump ................................................................................................................ 53 3.3 Frictional Losses in the Pipe ....................................................................................... 54 3.4 Friction Losses in Oil Filter ........................................................................................ 55 3.5 Pressure Drop in the Crankshaft ............................................................................... 56 7 3.6 Pressure Drop in the Connecting Rod ....................................................................... 57 3.7 Results for Pressure Drop in the Engine ................................................................... 58 Chapter 4 Hydraulic Models.......................................................................................... 60 4.1 Uni-Flow Model ........................................................................................................... 61 4.1.1 Mode of Operation ....................................................................................................... 61 4.1.2 Model Analysis ............................................................................................................ 63 4.1.3 Results for Uni-Flow Model Double-Cycle ................................................................. 67 4.1.4 Results for Uni-Flow Model Multi-Cycle .................................................................... 74 4.2 Double-Flow Model ..................................................................................................... 77 4.2.1 Mode of Operation ....................................................................................................... 77 4.2.2 Model Analysis ...........................................................................................................