DESIGN, FABRICATION, AND TESTING OF A FUEL-EFFICIENT ENGINE TRANSMISSION SYSTEM OF A PROTOTYPE VEHICLE AND BODY AERODYNAMICS EVALUATION
ABSTRACT
This project entails the design construction and test evaluation of an energy efficient go-cart engine and transmission system.
A target of 100km/l of fuel is set, having the knowledge that weight plays a major role in the efficiency of any vehicle using internal combustion engines; and also the aerodynamics of the vehicle body design is equally important as well. Aluminium profiles are used to construct and fabricate the chassis while wooden board is used for floor covering. Care is taken to reduce any excessive weights by cutting off parts that do not contribute to the structural integrity of the vehicle or which its contribution is highly negligible.
A CRF70 series engine was selected for the design with a net torque of 7.1Nm, with the required torque compensated for using a gear ratio of 1:3. The vehicle design acquiesces with the Shell Eco-Marathon Global Rules for the prototype gasoline category; which implies that there are design requirements and rules which must be met and not to be exceeded. For instance, a need for idling when the engine is cranked. The engine is installed behind the bulkhead separating the driver compartment from the engine compartment and rubber dampers of known damping coefficient are used to check the effect of vibration of the engine. A fuel tank of 250ml is used as reservoir for the gasoline while a chain drive mechanism is used to transmit power from the engine to the rear-wheel shaft on which the rear wheel is mounted; this in turn moves the entire vehicle. Care is taken to ensure fine tuning of the carburettor to avoid so much fuel consumption. After series of testing, the vehicle participated in the just concluded 2016 Shell Eco Marathon Challenger event held in South Africa which is one of the most genuine student engineers’ competition in the world where students in universities all over the world are challenged to design, fabricate and drive the ultimate energy efficient vehicles.
A result of 52.54km/l of fuel was recorded at the event computed using standard international algorithms as against 48km/l which was estimated. This implies acceleration, temperature of fuel and aerodynamic drag are all factors that contribute to the efficiency of any vehicle. This result of 52.52km/l is about 52.54% of the set target.
From the results, for a better performance an injector type engine should be used, that is the carburettor should be replaced by electronic fuel injection kits. Carbon fibre would
TABLE OF CONTENT
LIST OF ABBREVIATIONS ........................................................................................................................... iv
LIST OF FIGURES ........................................................................................................................................... v
LIST OF TABLES ........................................................................................................................................... vi
ABSTRACT ................................................................................................................................................... vii
CHAPTER ONE ............................................................................................................................................... 1
1.0 INTRODUCTION............................................................................................................................ 1
1.2 STATEMENT OF THE PROBLEM ........................................................................................... 3
1.3 AIMS AND OBJECTIVES .......................................................................................................... 3
1.4 SIGNIFICANCE OF THE WORK ............................................................................................. 4
1.5 SCOPE OF RESEARCH ............................................................................................................. 4
CHAPTER TWO .............................................................................................................................................. 5
2.0 LITERATURE REVIEW ................................................................................................................ 5
2.1 Brief History of Go-Cart .................................................................................................................. 6
2.2 TRANSMISSIONS........................................................................................................................... 7
2.3 TRANSMISSION USED FOR GO CART VEHICLES: .............................................................. 13
2.3.1 Manual Transmission ............................................................................................................. 13
2.3.2 Evolution Super Mileage Team .............................................................................................. 14
2.3.3 Alerion Super mileage ............................................................................................................ 14
2.3.4 Project Infinity ....................................................................................................................... 14
2.3.5 University of Science of Malaysia .......................................................................................... 14
2.3.6 Eco Illini ................................................................................................................................. 14
2.3.7 Team Green ............................................................................................................................ 15
2.3.8 Eco lancers .............................................................................................................................. 15
2.4 VEHICLE BODY DESIGN: .......................................................................................................... 16
CHAPTER THREE ...................................................................................................................................... 18
3.0 METHODOLOGY......................................................................................................................... 18
3.1 MATERIALS ................................................................................................................................. 18
3.2 DESIGN REQUIREMENTS/CONSIDERATIONS ..................................................................... 19
3.5 DESIGN CONCEPTS AND COMPONENTS SELECTION ....................................................... 19
3.6 DESCRIPTION OF THE SELECTED DESIGN ......................................................................... 20
3.6.1 ENGINE: CRF70 Series ......................................................................................................... 20
3.6.2 WHEEL AND TYRES: .......................................................................................................... 20
3.6.3 TRANSMISSION SYSTEM: ................................................................................................. 21
3.6.4 GEAR SELECTION MECHANISM AND ACTUATION SYSTEM: ................................. 21
3.7 MATERIALS SELECTION .......................................................................................................... 21
3.8 DESIGN CALCULATIONS .......................................................................................................... 22
3.8.1 TORQUE, POWER AND GEAR RATIO ............................................................................. 22
3.8.2 Calculation for Maximum Speed of Go-Cart ........................................................................ 24
3.8.3 DESIGN OF STATIONARY SHAFT FOR REARWHEEL ASSEMBLY .......................... 26
3.8.4 DESIGN OF THE CHAIN DRIVE SYSTEM: ............................................................................ 28
3.9 VEHICLE BODY DESIGN ........................................................................................................... 34
3.9.1 CHASSIS DESIGN: ............................................................................................................... 34
3.9.2 AERODYNAMICS: ............................................................................................................... 35
3.9.3 SAFETY: ................................................................................................................................ 37
3.9.4 WEIGHT: ............................................................................................................................... 37
3.9.5 STABILITY: .......................................................................................................................... 37
3.8 MATERIAL SAFETY AND DATA SHEET (MSDS) .................................................................. 38
CHAPTER FOUR ........................................................................................................................................... 39
4.0 RESULTS AND DISCUSSION ..................................................................................................... 39
4.2 TEST EVALUATION ..................................................................................................................... 44
4.3 BILL OF ENGINEERING MEASUREMENTS AND EVALUATION (BEME) ............................. 45
CHAPTER FIVE............................................................................................................................................. 46
CONCLUSION AND RECOMMENDATIONS .......................................................................................... 46
CONCLUSION ....................................................................................................................................... 46
RECOMMENDATIONS ......................................................................................................................... 47
REFERENCES ............................................................................................................................................... 48
APPENDIXES ................................................................................................................................................ 49
APPENDIX A: ............................................................................................................................................ 49
APPENDIX B: ................................................................................................................................................ 50
CHAPTER ONE
1.0 INTRODUCTION
Since the inception of the first steam engines, technology of engines and the method of transmission of
the power generated by these engines have evolved over the years with the advent of the diesel, gasoline
engines to mention a few.
Chaitanya Sharma et al, (2014) according to his study, insisted that there are growing demand for fossil
fuel like diesel and petrol to power automotive and cater other needs of human and as such Fossil fuels
are being depleted because of their excessive use and limited stocks.
In a country like Nigeria where the demand for fuel is over the bar and there is a recent hike in the price
of premium motor spirit (PMS), there is need for a better means of fuel consumption and efficiency in
automobiles and possible alternatives to fossil fuel.
In addition, the use of fossil fuels results in the pollution of the environment. In metro cities like Delhi,
Beijing, the level of pollution from vehicles during peak hour is dangerous; and because of this, people
are fragile and wear mask for filtering the polluted air for respiration. (Wikipedia, 2016)
Furthermore, there are frequent traffic jams on the road due to this there is wastage of fuel and time. All
these factors are responsible for various problems in human such as headache, stress, reduced
performance and so on. To minimize all these problems and to keep our earth free from pollution and
human health and fitness, there is an urgent need to seek better means of efficient fuel combustion in IC
engines.
Efforts are being put to develop vehicle powered by solar energy, hydrogen, biodiesel and batteries. The
movement of mechanical devices is a function of the rotational mechanisms involved and is subject to
it. An engine is the prime mover of most equipment and functions in relation to other fixed and attached
components. In this regard, an automobile engine provides the torque required to propel the vehicle via
its transmission system initiated by a gear and other related mechanisms.
The efficiency of any vehicle would depend much on the method in which the power or torque is
transmitted to the wheels of the vehicle. There are various means in which engineers have utilized in the
transmission of power. Most recently is the four-wheel drive transmission mechanism in which the
power is divided equally amongst the four wheels of a standard automobile and supplied at the same
time.
1
Usually, a rear transmission mechanism is used where the power generated at the engine is transmitted
using shafts to propel the rear wheels,
The simplest transmissions, often called gearboxes to reflect their simplicity (although complex systems
are also called gearboxes in the vernacular), provide gear reduction (or, more rarely, an increase in
speed), sometimes in conjunction with a right-angle change in direction of the shaft (typically
in helicopters). These are often used on power-take-off (PTO)-powered agricultural equipment, since
the axial PTO shaft is at odds with the usual need for the driven shaft, which is either vertical (as with
rotary mowers), or horizontally extending from one side of the implement to another (as with manure
spreaders, flail mowers, and forage wagons). More complex equipment, such as silage choppers
and snow blowers, have drives with output in more than one direction.
In the drive train, power is produced by the engine and transferred to the wheels to propel the vehicle.
Drive train helps to transfer power produced from the engine to the wheels with the help of intermediate
linkages. The set of linkages in between the engine and the wheels constitute the drive train. It includes
the clutch, the gearbox, the universal joints and the drive shaft and the differential arrangement.
The function of the clutch is to provide gradually increasing amount of power to the shaft, while the
engine output remains fixed. For better understanding, vehicle requires more power when it just starts
to roll (it needs to overcome inertia); but at this point in time the speed is very low. Since the engine is
connected to the wheels rigidly through gears and shafts, the engine also moves slowly. Since a slow
revolving engine produces little power which is not sufficient to accelerate, more power is produced if
it runs at high RPMs. In order to couple an engine running at high speed with a gear system running at
low speed, a clutch is introduced which connects the engine and the gear non-rigidly.
1.1 BACKGROUND OF THIS STUDY
This study analyses the efficiency of the engine and transmission systems of the car and its performance
for optimal values for the mechanical efficiency, fuel consumption, power and torque outputs, mean
effective pressure (mep). A fundamental aspect of this study is the modification of the engine for less
fuel consumption, torque and power output values for efficient performance. This involves conversion
of the engine from carburettor to electronic fuel injection system, utilization of centrifugal clutch
transmission system, aerodynamics of vehicle design (including the shape, frontal area, drag coefficient,
rolling resistance).
According to (Wikipedia, 2016), engine tuning is a modification of the internal combustion engine or
modification of its control unit, (Engine Control or ECU). It is performed to yield optimal performance,
to increase an engine’s power output, economy, or durability.
Shehata & Abdel (2008) stated that engine produces its maximum power at engine speed where the
power increase provided by the frequency of cycles is completely balanced by the decrease in torque.
1.2 STATEMENT OF THE PROBLEM
The problem and challenges resulting from the usage of automobiles in the day-to-day activities as
enlisted below has led to the embarking on this project. These are:
· Poor energy efficiency in the combustion of fuels used in vehicles leading to fuel wastage and
high cost.
· Increased fuel price regardless of the present state of the Nigerian economy leading to a high
cost of running automobiles
· Environmental Pollution due to incomplete combustion of fuel in the combustion chamber of
typical automobile engines.
· Improper power to weight ratio of vehicles resulting in inability to climb hills of certain degrees
and/or more energy consumption in doing so.
· Increased vehicle drags due to poor streamlining of body aerodynamics.
1.3 AIMS AND OBJECTIVES
The aim of this project is to achieve a target distance of one hundred kilometres (100km) in one litre of
fuel with the design of an efficient engine transmission system and aerodynamic body of a prototype
vehicle.
The objectives of this project are:
· To design and construct an enhanced transmission system utilizing centrifugal clutch and a chain
drive mechanism.
· To perform stress analysis on the vehicle body using finite element methods to check for
principal stresses and deformation.
· To carryout test evaluation of energy efficiency of the vehicle.
1.4 SIGNIFICANCE OF THE WORK
The significance of this work is to proffer new ideas for the automobile industry in the areas of fuel
efficiency and alternative for the automobile industry in the changing fuel market economy as well as
foster faster and safer mobility of persons, goods and commodities. Also, to make our automobiles eco-
friendlier and reduce green-house gases that are emitted to the atmosphere on a daily basis thereby
contributing our own quota to the reduction in the global warming effect that the earth is presently
experiencing. This project will thus provide cheaper and effective means for mobility of one man and
through the design an energy efficient prototype vehicle create a benchmark for future vehicle designs
(especially prototypes).
1.5 SCOPE OF RESEARCH
This research is limited to the design and fabrication of an efficient engine transmission system for a
prototype vehicle using a go-cart vehicle as case study, utilizing a single cylinder four-stroke spark
ignition engine and chain drive mechanism.
.