DESIGN OF AUTOMOTIVE PARTS FOR

5 AXIS MILLING MACHINE

KUAH CHUEN TSE

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

Design of Automotive Parts For

5 Axis Milling Machine

Thesis submitted in accordance with the partial requirements of the

Universiti Teknikal Malaysia Melaka for the

Bachelor of Manufacturing Engineering (Manufacturing Process)

By

Kuah Chuen Tse

Faculty of Manufacturing Engineering

May 2008

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

BORANG PENGESAHAN STATUS TESIS*

JUDUL: _______________________________________________________________ _______________________________________________________________ _______________________________________________________________

SESI PENGAJIAN : _______________________ Saya _____________________________________________________________________ mengaku membenarkan tesis (PSM/Sarjana/Doktor Falsafah) ini disimpan di Perpustakaan Universiti Teknikal Malaysia Melaka (UTeM) dengan syarat-syarat kegunaan seperti berikut:

1. Tesis adalah hak milik Universiti Teknikal Malaysia Melaka . 2. Perpustakaan Universiti Teknikal Malaysia Melaka dibenarkan membuat salinan

untuk tujuan pengajian sahaja. 3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran

antara institusi pengajian tinggi. 4. **Sila tandakan ()

(HURUF BESAR)

SULIT

TERHAD

TIDAK TERHAD

(Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia yang termaktub di dalam AKTA RAHSIA RASMI 1972)

(Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi/badan di mana penyelidikan dijalankan)

(TANDATANGAN PENULIS)

Alamat Tetap: Tarikh: _______________________

Disahkan oleh:

(TANDATANGAN PENYELIA)

Cop Rasmi:

Tarikh: _______________________

* Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah dan Sarjana secara penyelidikan, atau disertasi bagi pengajian secara kerja kursus dan penyelidikan, atau Laporan Projek Sarjana Muda (PSM). ** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD.

DECLARATION

I hereby, declared this thesis entitled Design of Automotive Parts For

5 Axis Milling Machine is the results of my own research

except as cited in references.

Signature : .

Authors Name :

Date :

i

ABSTRACT

Turbocharger is one of the approaches that utilize the exhaust gas of an automobile

to drive the compression device. The purpose of turbocharging is to increase the

intake pressure and the amount of air into the combustion chamber to improve the

efficiency of the engine. One of the main problems with turbochargers is that they do

not provide an immediate power boost when the accelerator pad is pressed, and the

car would accelerate forward suddenly when the turbocharger gets moving. This

study investigated how the design of a turbochargers turbine-compressor assembly

affects the efficiency of a turbocharger and improved the design of the turbine-

compressor assembly in term of transient response. Computational Fluid Dynamics

(CFD) program is used to simulate fluid flow of the design. And rapid prototype

machine is used to make a prototype of the turbine-compressor assembly. The major

contribution of this project is the design concept that can be implemented to other

turbocharger to reduce the effect of turbo-lag and improve the transient response of a

turbocharger.

Keywords: Turbocharger, Turbo-lag, CFD, Rapid prototype.

ii

ABSTRAK

Turbocharger merupakan sejenis kaedah menggunakan gas ekzos dalam sesebuah

kenderaan untuk menjalankan unit pemampat. Tujuan menggunakan turbocharger

adalah untuk meningkatkan tekanan udara dan kuantiti udara yang memasuki ke

dalam enjin supaya meningkatkan kecekapan enjin. Satu masalah yang terdapat pada

turbocharger ialah ia tidak membekalkan boost dengan serta-merta dan kenderaan

akan memecut secara tiba-tiba apabila turbocharger mula bergerak. Projek ini

menyelidikkan kesan rekabentuk turbine dan compressor sesebuah turbocharger

terhadap kecekapannya. Rekabentuk turbine dan compressor baru akan dicadangkan

untuk menggurangkan kesan turbo-lag. Atur cara komputer dinamik bendalir (CFD)

digunakan untuk mengkaji pengaliran gas dalam turbocharger tersebut. Prototaip

Pesat (RP) mesin digunakan untuk membuat satu prototaip rekabentuk ini.

Sumbangan utama projek ini adalah konsep rekabentuk yang boleh digunakan untuk

turbocharger yang lain untuk mengurangkan kesan turbo-lag dan meningkatkan

kecekapan sesebuah turbocharger.

Kata kunci: Turbocharger, Turbo-lag, CFD, Prototaip Pesat

iii

DEDICATION

For my dearest mom and dad.

iv

ACKNOWLEDGEMENTS

This research was performed under the supervision of Mr. Taufik, whom I

would like to thank for the freedom granted in carrying out this project. I also would

like to express my deep appreciation for Mr. Taufik understanding regarding the

difficulties I had during the project.

I would like to gratefully acknowledge Mr. Shahrul for his consultation on

the CNC machining. I would like to express my appreciation to Mr. Halim and Prof.

Md. Dan for being my panels and that they spend time to evaluate my report.

A special thank to my friend, Mr. Jia Chang, for his help on the ANSYS

simulation. And to all my friends who we have worked together for our projects, I

could not achieve it without their support and encouragement.

Most of all, I would like to thank my parents, for their patience and support

all the years, I appreciate the sacrifices they have made for me.

v

TABLE OF CONTENTS

ABSTRACT ............................................................................................................... i

ABSTRAK .............................................................................................................. ii

DEDICATION............................................................................................................. iii

ACKNOWLEDGEMENTS......................................................................................... iv

TABLE OF CONTENTS...............................................................................................v

LIST OF TABLES..................................................................................................... viii

LIST OF FIGURES ..................................................................................................... ix

LIST OF ABBREVIATIONS AND SPECIALIZED

NOMENCLATURE .................................................................................................... xi

LIST OF APPENDICES............................................................................................. xii

CHAPTER 1 INTRODUCTION .................................................................................1

1.1 Background of Study ....................................................................... 1

1.2 Problem Statement ........................................................................... 2

1.3 Objective of PSM............................................................................. 3

1.4 Scope of Work ................................................................................. 3

1.5 Schematic of Project ........................................................................ 4

1.6 Gantt Chart....................................................................................... 5

CHAPTER 2 LITERATURE REVIEW ......................................................................6

2.1 Introduction...................................................................................... 6

2.2 Turbocharger and Turbocharging Techniques................................. 6

2.3 Turbocharger Lag .......................................................................... 10

2.4 Proposed Solutions to Reduce Turbocharger Lag ......................... 12

2.4.1 Hydraulic Assist System............................................................ 14

2.4.2 Air-injection system................................................................... 14

2.4.3 Hybrid turbocharging................................................................. 15

2.4.4 Variable Geometry Turbines (VGT).......................................... 17

2.4.5 Sequential Turbocharging.......................................................... 19

2.4.6 Power Assist Systems ................................................................ 21

2.4.7 Alternatives to the Turbocharger ............................................... 26

vi

2.5 Dynamics of Turbocharger ............................................................ 29

2.6 5 Axis CNC Milling Machine........................................................ 29

2.7 CAD/CAM..................................................................................... 30

2.8 ANSYS CFX.................................................................................. 31

CHAPTER 3 MATERIALS AND METHODOLOGY.............................................33

3.1 Introduction.................................................................................... 33

3.2 Methodology.................................................................................. 34

3.2.1 Phase 1: Conceptual and Planning............................................. 35

3.2.2 Phase 2: Design and Analysis .................................................... 35

3.2.3 Phase 3: Machining.................................................................... 36

3.2.4 Phase 4: Discussion and Conclusion ......................................... 36

3.3 Material, Hardware and Software Requirement ............................ 36

3.4 Work Planning ............................................................................... 37

3.5 Method to Conduct an ANSYS simulation.................................... 39

3.5.1 Step 1 Pre-Processor: Geometry Creation .............................. 39

3.5.2 Step 2 Pre-Processor: CFX Meshing ...................................... 39

3.5.3 Step 3 Pre-Processor: Physics Preprocessor ........................... 40

3.5.4 Step 4 Simulation in ANSYS Solver ...................................... 41

3.5.5 Step 5 Post-Processing: Viewing the Results ......................... 41

CHAPTER 4 RESULTS ............................................................................................42

4.1 Introduction.................................................................................... 42

4.2 Technical Drawings ....................................................................... 42

4.2.1 Design 1 ..................................................................................... 43

4.2.2 Design 2 ..................................................................................... 47

4.3 Mass and Inertia Reports of Design .............................................. 51

4.3.1 Design 1 ..................................................................................... 51

4.3.2 Design 2 ..................................................................................... 52

4.4 Simulation Results ......................................................................... 53

CHAPTER 5 DISCUSSION......................................................................................58

5.1 Discussion on the Design............................................................... 58

5.1.1 Reduction in Volume and Masses ............................................. 59

5.1.2 Reduction on Inertia and Its Effect on Turbo-lag ...................... 59

vii

5.2 Design Selection ............................................................................ 60

5.3 Material Selection .......................................................................... 61

5.4 Discussion on the Simulation ........................................................ 62

5.4.1 The Simulation and Its Limitation ............................................. 62

5.4.2 Air Flow Path and Changes in Temperature.............................. 63

5.4.3 Pressure Boost Obtained............................................................ 64

CHAPTER 6 CONCLUSION....................................................................................65

REFERENCES ............................................................................................................66

APPENDIX .............................................................................................................69

viii

LIST OF TABLES

Table 2-1: Summary of the Comparison Results for the First Gear Acceleration 24

Table 2-2: Summary of the Comparison Results for the Third Gear Acceleration 24

Table 3-1: Hardware and Software Requirement 36

Table 3-2: Work Breakdown Structure of Project 37

Table 4-1: Summary of Simulation 57

Table 5-1: Comparison between Design 1 and 2 60

Table 5-2: Concept Scoring Matrix 61

ix

LIST OF FIGURES

Figure 1-1: Gantt Chart of PSM 1 5

Figure 1-2: Gantt Chart of PSM 2 5

Figure 2-1: Inlet and Exhaust Gas Flow Through a Turbocharger 7

Figure 2-2: The Effect of Turbine and Compressor Wheel Size on Acceleration

Response Time to Reach Designed Maximum Boost Pressure 11

Figure 2-3: A Schematic of a Hyperbrid Supercharging System 16

Figure 2-4: VGT Turbocharger 17

Figure 2-5: Engine Speed, Vehicle Speed, Inlet Manifold Pressure and Fuel Injected

Histories during Full Power Acceleration From 0 to 60 mph. Results

Obtained by Comparing the Conventional and the VGT Turbocharger 18

Figure 2-6: BMW 535D Turbocharger System Concept 20

Figure 2-7: Twin Turbo Parallel Configuration 20

Figure 2-8: Diesel Engine with an Electric Motor in a Parallel Hybrid Configuration,

where Pem Denotes the Supplemental Power 22

Figure 2-9: Diesel Engine with a Turbocharger Power Assist System, where Pem

Denotes the Supplemental Power 23

Figure 2-10: Comparison of Torque Characteristics and Acceleration Response With

and Without TPAS 23

Figure 2-11: Comparison of Compressor Acceleration Speeds for Different Levels of

Assist Power 25

Figure 2-12: Types of Mechanical Supercharger: (a) Rotating Lobe (b) Sliding Vane

(c) Rotating Impeller (d) Orbiting Spiral 27

Figure 2-13: CFD Design Iteration 32

Figure 3-1: Flow Chart of the Project 34

Figure 3-2: ANSYS CFX Flow chart 39

Figure 4-1: Compressor Design 1 43

Figure 4-2: Compressor Design 1 44

Figure 4-3: Turbine and Shaft Design 1 45

Figure 4-4: Turbine-Compressor Assembly Design 1 46

x

Figure 4-5: Compressor Design 2 47

Figure 4-6: Compressor Design 2 48

Figure 4-7: Turbine and shaft Design 2 49

Figure 4-8: Turbine-Compressor Assembly Design 2 50

Figure 4-9: (A) Geometry imported into ANSYS Modeler; 53

Figure 4-10: Flow path streamline 1 54

Figure 4-11: Detailed temperature streamline profile at compressor side. 55

Figure 4-12: Simulation Summary 57

Figure 5-1: Bottom of compressor 58

Figure 5-2 Temperature change at the compressor side. (A) Top view; (B) 3D view;

(C) Back view; and (D) Front view. 63

xi

LIST OF ABBREVIATIONS AND SPECIALIZED

NOMENCLATURE

CAD - Computer-aided Design

CAD/CAM - Computer-aided Design and Computer-aided Manufacturing

CAE - Computer-aided Engineering

CAM - Computer-aided Manufacturing

CATIA - Computer Aided Three Dimensional Interactive Application

CFD - Computational Fluid Dynamics

CFX - Advanced Computational Fluid Dynamics

CNC - Computer Numerical Control

ECU - Engine Control Unit

FEA - Finite Element Analysis

MRR - Material Removal Rate

NA - Naturally Aspirated

PLM - Product Lifecycle Management

TPAS - Turbocharger Power Assist System

VGT - Variable Geometry Turbine

WBS - Work Breakdown Structure

xii

LIST OF APPENDICES

Figure A: Housing Model 69

Figure B: Housing Model (Iso) 70

1

CHAPTER 1 INTRODUCTION

1.1 Background of Study

Automobile has become the most common and most important mean of

personal transportation. Millions of people around the world depend on their vehicle

to travel here and there. The origin of the automobile can be traced to Europe. It was

not common for people to own a car by then due to cars was so expensive. After a

century of the automobile, today, more and more people own cars.

Engine is sometimes described as the heart of an automobile. Engine is where

the burning of a mixture of fuel and air takes place and it produces mechanical

energy to drive the automobile. However, engine cannot work by itself; it has to

work together with other automotive parts, for instant, the manifold system. While

new engines are not redesigned very frequent, it has the necessity to undertake major

redesign of the manifold systems on a more regular basis, as mentioned by

Winterbone and Pearson (1999) in their studies.

Winterbone and Pearson (1999) explained how the intake and exhaust

manifolds affect engine performance, as well as emissions of noise and pollutants.

The potential for energy release in the combustion process, which is manifested as

the indicated mean effective pressure or the torque generated, is related to the

amount of air entering the cylinders. The majority of engines used in automobile

applications is naturally aspirated and operate on the four-stroke cycle, in which

distinct strokes of the piston are used to induce the air and exhaust it. There are also

other means to introduce the air into the cylinders. The most common methods are

2

supercharging, which uses a prime mover to drive the compression device; and

turbocharging, a method which utilize the exhaust gas to drive the compression

device. These methods are having the same objective that is to increase the intake

pressure and the amount of air into the combustion chamber; thus improving the

efficiency of the engine. Generally speaking, a turbocharger is more efficient than a

centrifugal supercharger. The scope of this study will be limited on the turbocharging

method only.

This study will investigate how the design of a turbochargers turbine-

compressor assembly affects the efficiency of a turbocharger and will try to improve

the design of the turbine-compressor assembly. Furthermore, finite element analysis

will be done on the redesigned models of the assembly to validate the designs. This

study also included machining the prototype of turbine and compressor. 5-axis CNC

machining will be used for the machining of the parts.

1.2 Problem Statement

One of the main problems with turbochargers is that they do not provide an

immediate power boost when the accelerator pad is pressed, and the car accelerate

forward suddenly when the turbo gets moving. Usually a delay is produced between

pressing on the accelerator pedal and the boost. This is due to the loss of energy to

overcome the rotational inertia of the turbine rotor. This problem is usually described

as turbo-lag (Nice, n.d.).

3

1.3 Objective of PSM

The aims of this project are to:

(a) Study and improve the design of a turbocharger turbine-compressor

assembly.

(b) Fabricate a prototype of the design using 5 axis CNC machine.

1.4 Scope of Work

The automotive part chosen for this project is the turbine-compressor

assembly inside a turbocharger. The purpose of this project is to study and improve

the design of the turbine-compressor assembly. The main focus is on the turbo-lag.

The cause of Turbo-lag will be studied and improved in the project.

In addition, a prototype of the model will be fabricated by using 5-axis CNC

machining. Before the real machining takes place, machining simulation will be

performed using CATIA; and the NC code will be generated. The parameters, for

instance, feed, speed, and material removal rate (MRR) involved in the machining

will be recorded as well.

4

1.5 Schematic of Project

Chapter 1 describes about the background of the study, project problem

statement, and the objective and scope of the study.

Chapter 2 highlighted some literature reviews related to the study, which

includes descriptions on turbocharger, turbo-lag, proposed technical solutions for

turbo-lag, CNC machining, CAD/CAM, and ANSYS CFX.

Chapter 3 shows the methodology and the flow of this project in detail from

the beginning.

Chapter 4 includes the result of the analysis and the presentation of data.

Chapter 5 provides a general discussion on the design, the results of the study,

stressing the significance and implications of the findings of the study.

Chapter 6 makes a conclusion on the study. Suggestions for future study are

included in this section as well.

5

1.6 Gantt Chart

Gantt chart has been built to give a visual presentation of the schedule of the

project flow. It shows the general sequence of project activities. Gantt chart is as well

a very useful tool to assist in tracking and monitoring the project progress. Figure 1-1

and Figure 1-2 below are the Gantt charts of the PSM 1 and PSM 2.

Figure 1-1: Gantt Chart of PSM 1

Figure 1-2: Gantt Chart of PSM 2

6

CHAPTER 2 LITERATURE REVIEW

2.1 Introduction

This section highlights some literature reviews related to the study. Firstly, an

overview of turbocharger, its significance, and its applications are presented.

Secondly, turbo-lag and its proposed technical solutions are being highlighted.

Finally, reviews of CAD/CAM and ANSYS CFX are presented.

2.2 Turbocharger and Turbocharging Techniques

Turbochargers are a type of forced induction system that compresses the air

flowing into the engine. Compressing the air introduces more air into the engine, and

more air means that more fuel can be added. Thus, more power can be provided by

the combustion process and in other word, the efficiency or power-to-weight ratio for

the engine is improved. The flow of gas through a turbocharger is shown in Figure

2.1.

The turbocharger itself is rather a simple device; the typical turbocharger

consisting a single turbine attached by a shaft to a single compressor. The operation

of a turbocharger is explained in detail by Aaron Joseph King (2002) in his research.

The turbine is driven by the exhaust gas at high temperature and pressure from the

exhaust manifold. The work of the turbine drives the compressor, and the air entering

the intake manifold is compressed. Although this arrangement seems simple, due to

its inherently unsteady operating environment, turbocharger design process is still

7

quite complex. Despite the complications of transient operation of an engine, the

advantages associated with the implementation of a turbocharger are universally

accepted when applied to high efficiency diesel engines. Significant effort has been

aimed at improving the efficiency and power to weight advantages of turbocharged

engines.

Figure 2-1: Inlet and Exhaust Gas Flow Through a Turbocharger

Source: Nunney (2006)

Early turbocharging systems isolate the turbine from the inherently unsteady

exhaust flow by connecting a large exhaust plenum between the exhaust valves and

turbine. The plenum served to dampen the transient exhaust pulsations, allowing the

turbocharger to operate in an essentially steady pressure environment. This technique

is called constant pressure turbocharging. Due to the isenthalpic expansion process,

constant pressure turbocharging decreases available energy to the turbocharger. It

also results in a system of high volumetric capacitance, which degrades the system

response time to engine accelerations and decelerations.

Therefore, in an effort to utilize more of the energy available from the

exhaust flow, a technique known as pulse turbocharging has been developed and

become the dominant technology. Pulse turbocharging minimizes the expansion

losses by attaching the turbocharger to a small exhaust manifold, subjecting the

turbocharger to the full transient of the discrete exhaust valve events. The net loss is

8

less than that which occurs in the larger manifolds of a constant-pressure system, but,

as a trade-off, the efficiency of the turbocharger subjected to pulsating flow is

typically lower. A detailed description of pulse turbocharging has been given by

Heywood (1998).

Turbochargers increase the efficiency and performance of diesel engines by

extracting more power out of a given engine. Recycling energy from exhaust gases,

turbochargers use that gas to turn a turbine, which in turn spins an air pump, which

subsequently forces compressed air into the engines cylinders. Without a

turbocharger, a diesel engine does not accelerate as fast as a gasoline engine.

However, a turbocharged diesel overcomes this by forcing more air into the engine.

Honeywell estimates the turbo effect of adding a turbocharger to a regular

diesel engine to be 70% additional fuel economy. According to a marketing research

of Gabelli & Company, Inc. in 2004, the global turbocharger market is

approximately 15 million units. Turbochargers are sold, on average, for about $200

each. According to the researcher of the report, David (2004), Turbochargers in the

personal vehicle market represent a significant opportunity for the turbocharger or

turbocharged engine manufacturers and companies.

Thus, due to the market opportunities of turbochargers, continuous efforts

have been made to improve efficiency and matching of rotary machines with internal

combustion engine over the widest possible range of operating conditions.

Ceausu (2006) mentioned that the typical boost provided by a turbocharger is

6 to 8 psi. Since normal atmospheric pressure is 14.7 psi at sea level, turbocharger is

getting about 50 percent more air into the engine. Therefore, 50 percent more power

is expected to obtained. However, nothing is perfectly efficient, so a 30- to 40-

percent improvement might be obtained instead.

The turbocharged direct injected diesel engine has become an attractive

alternative to gasoline engines on vehicle market. From the evolution of diesel