Electric and Hybrid Vehicles

Introduction to Hybrid Electric

Vehicles
What is a hybrid?
A hybrid vehicle combines any two power
(energy) sources. Possible combinations include
diesel/electric, gasoline/fly wheel, and fuel cell
(FC)/battery.
Typically, one energy source is storage, and the
other is conversion of a fuel to energy
 Difference between hybrid and
electric
• Thus to be a True hybrid, the vehicle must
have at least two modes of propulsion.
• For example, a truck that uses a diesel to drive
a generator, which in turn drives several
electrical motors for all-wheel drive, is not a
hybrid.
• But if the truck has electrical energy storage to
provide a second mode of operation(drive),
then it is a hybrid Vehicle
 critical issue in ev
• A critical issue for both battery life and safety
is the precision control of the
charge/Discharge cycle.
• Overcharging can be traced as a cause of fire
and failure
• The first limit, which is dictated by battery life, is the
minimum allowed State of Charge. As a result, not all
the installed battery energy can be used. The battery
feeds energy to other electrical equipment(drive),
which is usually the inverter. This equipment can use
a broad range of input voltage, but cannot accept a
low voltage.
• The second limit is the minimum voltage allowed
from the battery.
• State of charge (SoC) is the level of charge of an electric battery relative to its
capacity. The units of SoC are percentage points (0% = empty; 100% = full).
 Historical development (root) of
Automobiles
• In 1769, steam technology was advanced. The
advantages of steam-powered cars included
high performance in terms of power and
speed

Nicolas-Joseph
 components
• Feed water was a necessary input for steam
engine
• , Steam condensers were applied to the steam
car to solve the feed water problem.
• However, by that time Gasoline cars had won
the marketing battle.
• Gasoline cars of 1807 were noisy, dirty, smelly,
cantankerous(irritable), and unreliable.
• 1890
• In comparison, electric cars were comfortable,
quiet, clean, and fashionable. Easy of control
was also a desirable feature. Lead acid
batteries were used in 1900 and are still used
in modern cars. Hence lead acid Batteries have
a long history (since 1881) of use as a viable
energy storage device
• Golden age of Electrical vehicle marked from
1890 to 1924 with peak production of electric
vehicles in 1912. However, the range was
limited by energy storage in the battery. After
every trip, the battery required recharging.
• At the 1924 automobile show, no electric cars
were on display
 1924
• This announced the end of the Golden Age of
electric-powered cars.
• The range of a gasoline car was far superior to
that of either a steam or an electric car and
dominated the automobile market from 1924
to 1960. The gasoline car had one dominant
feature; it used gasoline as a fuel. The modern
period starts with the oil embargoes and the
gasoline shortages during the 1970s which
created long lines at gas stations.
 2000
• Engineers recognized that the good features
of the gasoline engine could be combined
with those of the electric motor to produce a
superior car. A marriage of the two yields the
hybrid automobile.
 Present of Hybrid Electric vehicle

• Toyota is the most prominent of all

manufacturers when it comes to hybrid cars
cars and SUVs, there are a select number of
hybrid motorcycles, pickups, vans, and other
road going vehicles available to the consumer
and the list is continually increasing.
 Future of Hybrid electrical vehicle

• Since petroleum is limited and will someday

run out of supply. In the arbitrary year 2037,
an estimated one billion petroleum-fueled
vehicles will be on the world’s roads.
• So year 2037 “gasoline runs out year” means,
petroleum will no longer be used for personal
mobility
• A market may develop for solar-powered EVs
of the size of a scooter or golf cart.
• Since hybrid technology applies to heavy
vehicles, hybrid buses and hybrid trains will be
more significant
1st topic end
 Social and Environmental
Importance of Hybrid & Electric
Vehicle
• As modern culture and technology continue to develop, the
growing presence of global warming and irreversible climate
change draws increasing amounts of concern from the world’s
population.
• • According to various reports, cars and trucks are responsible
for almost 25% of CO2. emission and other major
transportation methods account for another 12%.
• • Air pollution, global warming, and the rapid depletion of
the Earth’s petroleum resources are now problems of
paramount concern.
• • In recent decades, the research and development activities
related to transportation have emphasized the development
of high efficiency, clean, and safe transportation
• With immense quantities of cars on the road today, pure
combustion engines are quickly becoming a target of global
warming blame. One potential alternative to the world’s
dependence on standard combustion engine vehicles are
hybrid cars
• • Electric vehicles, hybrid electric vehicles, and fuel cell
vehicles have been typically proposed to replace conventional
vehicles in the near future.
• • The social and environmental problems like air pollution, gas
emissions causing global warming, and petroleum resource
depletion due to the use of conventional engines gave birth to
the development of electric vehicles, hybrid electric vehicles,
and fuel cell technology
 1) Air Pollution
• All vehicles rely on the combustion of hydrocarbon fuels to derive the
energy necessary for their propulsion. Combustion is a reaction between
the fuel and the air that releases heat and combustion products.
• The heat is converted to mechanical power by an engine and the
combustion products are released into the atmosphere. A hydrocarbon is
a chemical compound with molecules made up of carbon and hydrogen
atoms.
• Ideally, the combustion of a hydrocarbon yields only carbon dioxide and
water, which do not harm the environment. Actually, the combustion of
hydrocarbon fuel in combustion engines is never ideal.
• Besides carbon dioxide and water, the combustion products contain a
certain amount of nitrogen oxides (NOx), carbon monoxides (CO), and
unburned hydrocarbons (HC), all of which are toxic to human health.
 B) Global Warming
• Global warming is a result of the “greenhouse effect” induced by the presence of
carbon dioxide and other gases, such as methane, in the atmosphere.
• • These gases trap the Sun’s infrared radiation reflected by the ground, thus
retaining the energy in the atmosphere and increasing the temperature.
• • An increased Earth temperature results in major ecological damages to its
ecosystems and in many natural disasters that affect human populations.
• • Global warming is believed to have induced meteorological phenomena such as
“El Niño,” which disturbs the South-Pacific region and regularly causes tornadoes,
inundations, and dryness.
• • The melting of the polar icecaps, another major result of global warming, raises
the sea level and can cause the permanent inundation of coastal regions, and
sometimes of entire countries.
• • Carbon dioxide is the result of the combustion of hydrocarbons and coal.
• • Transportation accounts for a large share (32% from 1980 to 1999) of carbon
dioxide emissions.
• Figure 2 shows the trend in carbon dioxide
emissions. The transportation sector is clearly
now the major contributor of carbon dioxide
emissions. It should be noted that developing
countries are rapidly increasing their
transportation sector, and these countries
represent a very large share of the world’s
population.
C) Depletion of Petroleum
Resources
 Advantages of Hybrid Vehicles
• • The electric motor is far more efficient (70%-85% efficiency)
than the heat engine.
• • EV’s can use regenerative braking (regain 30% of energy
used, theoretically).
• • HEV’s are more environmentally friendly (if electricity if
produced from renewable sources)
• • Reduction in engine and vehicle weight
• • Fuel efficiency is increased
• • Emissions are decreased
• • Cut emissions of global warming pollutants by 1/3 or ½
• • Reduce the dependency on fossil fuels
• • ~2 times more efficient than conventional engine
 VARIOUS ISSUES REGARDING
HYBRID VEHICLES
• In the majority of modern hybrids are powered by
a combination of traditional gasoline power and the
addition of an electric motor.
• However, hybrid still use the petroleum based
engine while driving so they are not completely
clean, just cleaner than petroleum only cars.
• This enables hybrid cars to have the potential to
segue (ove without interruption ) into new
technologies that rely strictly on alternate fuel
sources.
 electric car pollution significantly
depends on the source of the
electricity:
• The economics and environmental impact associated with
use of an electric car depends significantly on the source of
the electricity:
• a. If electricity is generated from renewable energy sources,
the EV is advantageous to the hybrid vehicle.
• b. If the electricity is generated from fossil fuels, the electric
car remains competitive only if the electricity is generated
onboard.
• c. If the electricity is generated with an
efficiency of 50–60% by a gas turbine engine
connected to a high-capacity battery and
electric motor, the electric car is superior in
many respects.
• d. The EV with capability for onboard
electricity generation represents a beneficial
option and is worthy of further investigation,
as part of efforts to develop energy efficient
and ecologically benign vehicles.
Case study
(tutorial)
 Environmental Analysis

• Two environmental impact elements were

accounted for in the:
•
• Air pollution (AP) and
•
• Greenhouse gas (GHG) emissions.
• The main GHGs were CO2, CH4, N2O, and SF6
(sulfur hexafluoride), which have GHG impact
weighting coefficients relative to CO2 of 1, 21,
310, and 24,900, respectively.
•
• For AP, the airborne pollutants CO, NOx, SOx, and
VOC(volatile organic compounds paints,
pharmaceuticals, and refrigerants. )s are assigned
the following weighting coefficients: 0.017, 1, 1.3,
and 0.64, respectively.
• The vehicle production stage contributes to the
total life cycle environmental impact through the
pollution associated with
• The extraction and processing of material
resources,

• Manufacturing and

• The vehicle disposal stage.

GHG and air pollution emissions per
MJ of electricity produced
(for electric car)
Electricity- Description of Electricity generation GHG emission (g) APemission

generation Scenario (g)

scenario

1 Electricity produced = 100% (Renewable 5.11 0.195

Energy + Nuclear Energy)

2 Electricity produced = (50% Renewable 77.5 0.296

Energy + 50% Natural gas)

3 Electricity produced = 100% Natural Gas 149.9 0.573

GHG and air pollution emissions per
MJ fuel of Hydrogen from natural gas
produced(for fuel cell)
Fuel GHG emissions, g AP emissions, g

Hydrogen from natural gas

Scenario 1 78.5 0.0994

Scenario 2 82.1 0.113

Scenario 3 85.7 0.127

• The analysis were conducted on six vehicles, each
was representative of one of the above discussed
categories. The specific vehicles were:
• Toyota Corolla (conventional vehicle),
• Toyota Prius (hybrid vehicle),
• Toyota RAV4EV (electric vehicle),
• Honda FCX (hydrogen fuel cell vehicle),
• Ford Focus H2-ICE (hydrogen ICE vehicle),
• Ford Focus H2-ICE adapted to use ammonia as
source of hydrogen (ammonia-fueled ICE vehicle).
 Environmental impact associated with
vehicle Overall Life cycle and Fuel
Utilization State
Fuel utilization stage Overall life cycle

Vehicle type GHG emissions AP emissions GHG emissions AP emissions

(kg/100 km) (kg/100 km) (kg/100 km) (kg/100 km)

Conventional 19.9 0.0564 21.4 0.06

Hybrid 11.6 0.0328 13.3 0.037

Electric-S1 0.343 0.00131 2.31 0.00756

Electric-S2 5.21 0.0199 7.18 0.0262

Electric-S3 10.1 0.0385 12 0.0448

Fuel Cell -S1 10.2 0.0129 14.2 0.0306

Fuel Cell -S2 10.6 0.0147 14.7 0.0324

Fuel Cell -S3 11.1 0.0165 15.2 0.0342

H2-ICE 10 0.014 11.5 0.018

NH3–H2-ICE 0 0.014 1.4 0.017

 Economical Analysis

• A number of key economic parameters that

characterize vehicles were:

• Vehicle price,

• Fuel cost, and

• Driving range.
Vehicle type Fuel Type Initial Specific fuel Driving Price of battery Changes

Price Price Range During Vehicle Life

(USk$) (US$/100 km) (Km) cycle (USk$)

Conventional Gasoline 15.3 2.94 540 1 x 0.1

(Toyota Corolla)

Hybrid Gasoline 20 1.71 930 1 x 1.02

(Toyota Prius)

Electric Electricity 42 0.901 164 2 x 15.4

(Toyota RAV4EV)

Fuel cell Hydrogen 100 1.69 355 1 x 0.1

(Honda FCX)

H2-ICE (Ford Hydrogen 60 8.4 300 1 x 0.1

Focus H2 -ICE)

NH3–H2-ICE Ammonia 40 6.4 430 1 x 0.1

(Ford Focus H2 -

ICE and ammonia

Adaptive)
 Results of technical–economical–
environmental Analysis:
• This analysis showed that the hybrid and
electric cars have advantages over the others.
The economics and environmental impact
associated with use of an electric car depends
significantly on the source of the electricity
• If electricity is generated from renewable energy
sources, the electric car is advantageous to the hybrid
vehicle.
•
• If the electricity is generated from fossil fuels, the
electric car not good
•
• If the electricity is generated with an efficiency of 50–
60% by a gas turbine engine connected to a high-
capacity battery and electric motor, the electric car is
superior in many respects.
•
2nd topic over
 Next topic
IMPACT OF MODERN DRIVE-TRAINS ON ENERGY
SUPPLIES
Impact on energy supplies (ev)
 Next topic,

CONVENTIONAL VEHICLES: BASICS

OF VEHICLE PERFORMANCE
 CONVENTIONAL VEHICLES

• Figure 2.8, consists of a power plant(engine or electric motor), a clutch in

manual transmission or a torque converter in automatic transmission, a
gearbox (transmission), final drive, differential, drive shaft, and driven
wheels
• With all vehicles the prediction of
performance and range is important.
• By performance we mean acceleration and
top speed.
• The first step in vehicle performance
modelling is to produce an equation for the
tractive effort.
 vehicle performance.
• 1.maximum cruising speed
• 2.Gradeability
• Acceleration Performance

a speed for a particular vehicle, ship, or aircraft, usually somewhat below maximum,
that is comfortable and economical.
 Basics
• The torque and rotating speed of the power
plant output shaft are transmitted to the drive
wheels through the clutch or torque
converter, gearbox, final drive, differential,
and drive shaft
• The clutch is used in manual transmission to
couple the gearbox to or decouple it from the
power plant
• The gearbox supplies a few gear ratios from its
input shaft to its output shaft for the power
plant torque–speed profile to match the
requirements of the load
 Torque on the driven wheels
• The final drive is usually a pair of gears that supply a further
speed reduction and distribute the torque to each wheel
through the differential .The torque on the driven wheels,
transmitted from the power plant, is expressed as
 Tractive Effort

• Tractive Effort is the force propelling the

vehicle forward, transmitted to the ground
through the drive wheels
• Consider a vehicle of mass m, proceeding at a
velocity v, up a slope of angle ψ or ∝, as in
Figure. the tractive effort, has to accomplish
the following
• overcome the rolling resistance;
• overcome the aerodynamic drag;
• provide the force needed to overcome the
component of the vehicle’s weight acting
• down the slope; Uphill resistance
• accelerate (fla,fᶭa)the vehicle, if the velocity
is not constant.

Linear angular
The forces acting on a vehicle
moving (uphill) along a slope

Fla +fwa
Detailed explanation
(tutorial)
 Basics-understanding purpose
• 1)tractive force
• 2.Grade resistance
• 3.Resistance of vehicle
• 4.Rolling Resistance
• 5.Aerodynamic Drag
• 5.1.Shape drag
• 6.Grading Resistance(detailed)
 Basics terms :1)tractive force
• tractive force can either refer to the
total traction a vehicle exerts on a surface, or
the amount of the total traction that is parallel
to the direction of motion.
 3 types of tractive effort
• The term tractive effort is often qualified as 1)starting
tractive effort,2) continuous tractive
effort and3) maximum tractive effort
• These terms apply to different operating conditions,
but are related by common mechanical factors: input
torque to the driving wheels, the wheel
diameter, coefficient of friction (μ) between the driving
wheels and supporting surface, and the weight applied
to the driving wheels (m).
• The product of μ and m is the factor of adhesion,
which determines the maximum torque that can be
applied before the onset of wheelspin .
• Starting tractive effort: Starting tractive effort is the tractive force
that can be generated at a standstill. This figure is important on
railways because it determines the maximum train weight that a
locomotive can set into motion.
• Maximum tractive effort: Maximum tractive effort is defined as the
highest tractive force that can be generated under any condition
that is not injurious to the vehicle or machine. In most cases,
maximum tractive effort is developed at low speed and may be the
same as the starting tractive effort.
• Continuous tractive effort: Continuous tractive effort is the tractive
force that can be maintained indefinitely, as distinct from the higher
tractive effort that can be maintained for a limited period of time
before the power transmission system overheats.
• Due to the relationship between power (P), velocity (v) and force
(F), described as:P = vF or P/v = F
Tractive effort of a gasoline engine-powered vehicle
with multispeed transmission and its resistance
 6.Grading Resistance
• When a vehicle goes up or down a slope, its
weight produces a component that is always
directed in the downward direction,
• This component either opposes the forward
motion (grade climbing) or helpsthe forward
motion (grade descending).
• In vehicle performance analysis,only uphill
operation is considered. This grading force is
usually calledgrading resistance.
• Grading resistance, can be expressed as
• Fg = Mg sin α
 General Description of tire rolling
resistance
• the forces acting on a vehicle moving up a
grade. The tractive effort, Ft, in the contact
area between tires of the driven wheels and
the road surface propels the vehicle forward
• It is produced by the power plant torque and
is transferred through transmission and final
drive to the drive wheels. While the vehicle is
moving, there is resistance that tries to stop
itsmovement.
 3.Resistance of vehicle
• The resistance usually includes tire rolling
resistance, aerodynamic drag, and uphill
resistance.
• According to Newton’s second law, vehicle
acceleration can be written as
• rolling resistance torque Trf
• aerodynamic drag, Fw,
• grading resistance (the term=Mv g sin α)
 Vehicle Resistance
• Rolling Resistance
• Aerodynamic Drag
• Grading Resistance
 4.Rolling Resistance
• The rolling resistance of tires on hard surfaces
is primarily caused by hysteresis in the tire
materials. This is due to the deflection of the
carcass while the tire is rolling.
• Figure 2.2 shows a tire at standstill, on which a force, P, is
acting at its center. The pressure in the contact area between
the tire and ground is distributed symmetrically to the central
line and the resultant reaction force, Pz, is aligned to P.
 Hard surface
• When the tire is rolling, as shown in Figure 2.4a, the leading
half of the contact area is loading and the trailing half is
unloading. Consequently, the hysteresis causes an
asymmetric distribution of the ground reaction forces. The
pressure in the leading half of the contact area is larger than
that in the trailing half,
• This phenomenon results in the ground
reaction force shifting forward somewhat. This
forwardly shifted ground reaction force, with
the normal load acting on the wheel center,
creates a moment, which opposes rolling of
the wheel
 Soft surface
• On soft surfaces, the rolling resistance is
primarily caused by deformation of the
ground surface as shown in Figure
• The rolling resistance coefficient, fr, is a
function of tire material, tire structure,tire
temperature, tire inflation pressure, tread
geometry, road roughness,road material, and
presence or absence of liquids on the road
 road
resistance
• The tire rolling resistance and the grading
resistance taken together and is called road
resistance; Frd=Frr+Fhc= Mg(μrr cos(ψ)+ sin
(ψ))
 5.Aerodynamic Drag
• A vehicle traveling at a particular speed in air
encounters a force resisting its motion. This
force is referred to as aerodynamic drag. It
mainly results from two components:
• shape drag and skin friction.
 5.1.Shape drag
Shape drag: The forward motion of the vehicle pushes the
air in front of it.However, the air cannot
instantaneously move out of the way and its pressure is
thus increased, resulting in high air pressure.
• In addition, the air behind the vehicle cannot
instantaneously fill the space left by the forward
motion of the vehicle. This creates a zone of low air
pressure. The motion of the vehicle, therefore, creates
two zones of pressure that oppose the motion by
pushing (high pressure in front) and pulling it backwards
• The resulting force on the vehicle is the shape drag. The name “shape
drag” comes from the fact that this drag is completely determined by the
shape of the vehicle body
• Skin friction: Air close to the skin of the vehicle
moves almost at the speedof the vehicle while
air away from the vehicle remains still. In
between, airmolecules move at a wide range
of speeds. The difference in speed
betweentwo air molecules produces a friction
that results in the second component of
aerodynamic drag
• Aerodynamic drag is a function of vehicle speed V,
vehicle frontal area, Af ,shape of the vehicle body, and
air density, ρ:

• where CD is the aerodynamic drag coefficient that

characterizes the shape of the vehicle body and Vw is
component of the wind speed on the vehicle
movingdirection, which has a positive sign when this
component is in the samedirection of the moving
vehicle and a negative sign when it is opposite to
the vehicle speed
aerodynamic drag coefficients
Factor affect: maximum tractive effort
of a vehicle
• There are two limiting factors to the maximum
tractive effort of a vehicle.
• maximum tractive effort that the tire–ground
contact can support tractive effort that the
power plant torque with given driveline gear
ratios can provide
• .
•
Next topic
 Mathematical
Models To Describe Vehicle
Performance.
• Vehicle In the longitudinal direction, the major
external forces acting on a two axle vehicle
include:
• The Rolling resistance of the front and rear
tires (Frf. and Frr.),.
• The Aerodynamic drag (Fw)
• Grade climbing resistance (Fg)
• Acceleration resistance (Fa)
• Consider a vehicle of mass m, proceeding at a
velocity v, up a slope of angle ψ or ∝, as in
• Figure. the tractive effort, has to accomplish the
following:
• overcome the rolling resistance;fr
• overcome the aerodynamic drag;fw
• provide the force needed to overcome the
component of the vehicle’s weight acting
• down the slope; Uphill resistance fg
• accelerate the vehicle, if the velocity is not constant
fa
 total Tire resistance

• total Tire resistance of vehicle Trf+Trr=Fr

=Fr = mg fr cos α*rd

fr.=rolling resistance coefficient, The rolling resistance

coefficient of a tire depends on tire construction, materials,
air pressure, vehicle speed, and road conditions grade
 • According to Newton's second law of motion
dynamic equation of vehicle motion along the
longitudinal direction is given by F = mv,f/m=v
where dV/dt is the
linear acceleration

,Ft=tractive force,m mass of vehicle,( del)δ=mass factor rotation to translational

• The first term on the right side is the total
tractive effort and the second term is the total
tractive resistance
• To find the maximum tractive effort that the
tire–ground contact can support, can be found
out by finding the normal loads on the front
and rear axles
V=velocity,fw wind force,trf rolling resistance front wheel,trr rolling resistance rear wheel
Wf-front wheel load,wr rear wheel load,L total length b/w wheels,o center of the tire–groun
area)
Mv.= Mass of the vehicle
g = Acceleration constant [m/s2.]
α = Road angle radians, [arodynamic resistance hw,] height of the gravity center of the
vehicle, hg
• By summing the moments of all the forces
about point R (center of the tire–ground area),
the normal load on the front axle Wf. can be
written as Rolling aerodynamic
Resistance grade r
resistance

Weight on front wheel

• Similarly, the normal load acting on the rear
axle Wr. can be expressed as

• For passenger cars, the height of the center of application of aerodynamic

resistance, hw, is assumed to be near the height of the gravity center of the vehicle,
hg.so hw=hg

Fg=Mvg sin α
rolling resistance magn
Fr = mg fr cos α*rd
where rd is the
effective radius of the ti
 Fr = mg fr cos α

static load on the front and rear axle dynamic component of the norma
• The first term on the right-hand side of above
2 equation is the static load on the front and
rear axle
• when the vehicle is at rest on level ground.
The second term is the dynamic component of
the normal load.
 road adhesion
• The maximum tractive effort (Ftmax) that the
tire-ground contact can support is described
by the product of the normal load and the
coefficient of road adhesion (μ).
• The adhesive capability between the tire and
the ground is sometimes the main limitation
of vehicle performance
• For the front wheel drive vehicle, Ftmax. is
given by

• For the rear wheel drive vehicle, Ftmax. is

given by
• Any small amount force given over this maximum
tractive effort will cause the tire to spin on the
ground.
.
Next topic
vehicle Power source
Characteristics
 1.Power source Characteristics
• For vehicular applications, the ideal
performance characteristic of a power plant is
the constant power output over the full speed
range
• Consequently, the torque varies with speed
hyperbolically as shown in Figure
 Expected n/t

0
• This constant power characteristic will provide the
vehicle with a high tractive effort at low speeds,
where demands for acceleration, drawbar pull, or
grade climbing capability are high.
• The IC engines are the most commonly used power
plants for the land vehicles.
• In hybrid and electric vehicle technology, the electric
motor is used.
 Ic vs electric
• Since the internal combustion engine and
electric motor are the most commonly
used power plants for automotive vehicles

• Characteristics of a gasoline engine in full

throttle and an electric motor at full load are
shown in Figure,
 Explanation of graph(ic)
• It starts operating smoothly at idle speed. Good
combustion quality and maximum engine torque are
reached at an intermediate engine speed.
• As the speed increases further, the mean effective
pressure decreases because of the growing losses in
the air-induction manifold and a decline in engine
torque
• . Power output, however, increases to its maximum at
a certain high speed. Beyond this point, the engine
torque decreases more rapidly with increasing speed.
This results in the decline of engine power output.
 Speed setting of engine
• vehicular applications, the maximum
permissible speed of the engine is usually set
just a little above the speed of the maximum
power output
Next topic
 2.Transmission Characteristics
• The transmission requirements of a vehicle
depend on the characteristics of the power
plant and the performance requirements of
the vehicle
• As mentioned previously, a well-controlled
electric machine such as the power plant of an
electric vehicle will not need a multi gear
transmission.
 Need of gear(ic)
• However, an internal combustion engine must
have a multi gear or continuously varying
transmission to multiply its torque at low
speed.
• For automobile applications, there are usually
two basic typesof transmission: manual gear
transmission and automatic transmission
 Modification by transmission

• Consequently, a multigear transmission is usually employed to modify

 Explanation :Electric motor
• Electric motors, however, usually have a speed–torque characteristic that
is much closer to the ideal, as shown in Figure.
• Generally, the electric motor starts from zero speed. As it increases to its
base speed, the voltage increases to its rated value while the flux remains
constant. Beyond the base speed, the voltage remains constant and the
flux is weakened. This results in constant output power while the torque
declines hyperbolically with speed.
• Since the speed–torque profile of an electric motor is close to the ideal, a
single-gear or double-gear transmission is usually employed, as shown in
Figure
 Types of torque converter
• 3 types
• Manual

• hydro dynamic

• Continuous variable type

 type1.
Manual Gear Transmission (torque
converter)
• Manual gear transmission consists of a clutch,
gearbox, final drive, and driveshaft as shown
in Figure 2.8
 gear
• The final drive has a constant gear reduction
ratio or a differential gear ratio.
• The gearbox provides a number of gear
reduction ratios ranging from three to five for
passenger cars and more for heavy
commercial vehicles that are powered with
gasoline or diesel engines.
 Roll of gear ratio
• The maximum speed requirement of the
vehicle determines the gear ratio of the
highest gear (i.e., the smallest ratio).
• On the other hand, the gear ratio of the
lowest gear (i.e., the maximum ratio) is
determined by the requirement of the
maximum tractive effort or the gradeability
 s2

S1
 Another Use of gear
• , gear ratios between the highest and the
lowestgear may be selected in such a way that
the engine can operate in the same speed
range for all the gears.
• This approach would benefit the fuel
economy and performance of the vehicle
• For instance, in normal driving,the proper gear can be selected according to
vehicle speed to operate the engine in its optimum speed range for fuel-saving
purposes. In fast acceleration ,the engine can be operated in its speed range with
high power output. This approach is depicted in Figure 2.16.
• The gear ratio is the ratio of the number of
turns the output shaft makes when the input
shaft turns once.

The gear ratio is the ratio of the number of turns the output shaft makes
when the input shaft turns once.
 Compare(single vs 4 gear)(ic vs ev)
• Figure 2.17 shows the tractive effort of a gasoline engine vehicle with four
geartransmission and that of an electric vehicle with single-gear transmission.
• It is clear that electric machines with favorable torque–speed characteristics
can satisfy tractive effort with simple single-gear transmission
tutorial
 types 2
torque converter
 Type 2.Hydrodynamic
Transmission/gear
•
(torque converter)
Hydrodynamic transmissions use fluid to transmit power in
the form of torque and speed and are widely used in
passenger cars. it consist of a torque converter and an
automatic gearbox. The torque converter consists of at
least three rotary elements known as the impeller (pump),
the turbine, and the reactor, as shown in Figure 2.18.
• a mechanism for step-
less change of torque transmitted from a motor or of the
rotational speed (rpm) of the shaft of a machine tool.
• A hydrodynamic transmission works by the action of a rota
ry pump and a turbine.
 Basic working
• The hydrodynamic transmission was proposed in
the beginning of the 20th century.
• Its design features a centrifugal pump
and a turbine, located coaxially in such a way that
their wheels form a toroidal cavity partially filled
with pressure fluid (low-viscosity oil or water).
• The fluid is impelled by the pump, which has a wh
eel connected to a motor. The energy received by
the fluid from the pump is transmitted by the tur
bine to a driven machine.
• In a hydrodynamic transmission having only two
wheels (a pump impeller and a turbine runner),
the torques on both shafts are equal.
• Such a transmission is called a hydro-
dynamic coupling (hydraulic clutch). In rated ope
ration of such a coupling,
the rpm of the turbine shaft is lower than the r
pm of the pump shaft by 5-4 percent.
• The efficiency of such a hydraulic clutches 95-
98 percent.
 Detailed explanation
• The impeller is connected to the engine shaft and the turbine is
connected to the output shaft of the converter, which in turn is
coupled to the input shaft of the multispeed gearbox.
• The reactor is coupled to external housing to provide a reaction on
the fluid circulating in the converter. The function of the reactor is
to enable the turbine to develop an output torque higher than the
input torque of the converter, thus producing torque multiplication.
• The reactor is usually mounted on a free wheel (oneway clutch) so
that when the starting period has been completed and the turbine
speed is approaching that of the pump, the reactor is in free rotation.
• Atthis point, the converter operates as a fluid coupled with a ratio
of outputtorque to input torque that is equal to 1.0.
 Advantages& disadvantages
The major advantages of hydrodynamic transmission may be summarized
as follows:

• When properly matched, the engine will not stall.

• It provides flexible coupling between the engine and the driven wheels.
• Together with a suitably selected multispeed gearbox, it provides torque–
speed characteristics that approach the ideal.

• The major disadvantages of hydrodynamic transmission are its low

efficiency in a stop–go driving pattern and its complex construction.
Torque converter characteristic
 capacity factor of torque converter
Kc,
• The capacity factor, Kc, is an indicator of the ability of the converter to
absorb or transmit torque, which is proportional to the square of the
rotary speed. Typical performance characteristics of the torque converter
are shown in

The difference between the speeds of the two gears is called the speed ratio or gear ra
 Graph explanation-torque
• torque ratio, efficiency, and input capacity factor
— that is the ratio of input speed to the square
root of input torque — are plotted against speed
ratio.
• The torque ratio has the maximum value at stall
condition, where the output speed is zero. The
torque ratio decreases as the speed ratio
increases (gear ratio decreases) and the
converter eventually acts as a hydraulic coupling
with a torque ratio of 1.0.
 Explanation-Efficiency
• At this point, a small difference between the
input and output speed exists because of the
slip between the impeller (pump) and the
turbine. The efficiency of the torque converter
is zero at stall condition and increases with
increasing speed ratio (decrease inthe gear
ratio). It reaches the maximum when the
converter acts as a fluid coupling (torque ratio
equal to 1.0)
 engine capacity factor, Ke
• To determine the actual operating condition of the
torque converter, the engine operating point has to
be specified because the engine drives the torque
converter.
To characterize the engine operating condition for the
purpose of determining the combined performance
of the engine and the converter,an engine capacity
factor, Ke, is introduced and defined as…
where ne and Te are engine speed and torque,
respectively.
The variation of the capacity factor with speed
for a typical engine is shown in Figure 2.20.
To achieve proper matching, the engine and the
torque converter should have a similar range
in the capacity factor.
 Graph explanation
• The engine shaft is usually connected to the input shaft
of the torque converter, as mentioned above. That
is,Ke=Kc
• The matching procedure begins with specifying the
engine speed and engine torque.
• Knowing the engine operating point, one can
determine the engine capacity factor, Ke .
• Since Ke, Kc, the input capacity factor of the torque
converter corresponding to the specific engine
operating point is then known.

• .
The output torque and output speed of the
converter are then given by
 How to improve torque
• Since the torque converter has a limited torque ratio range (usually less
than 2), a multispeed gearbox is usually connected to it.
• The gearbox comprises several planetary gear sets and is automatically
shifted. With the gear ratios of the gearbox, the tractive effort and speed
of the vehicle can be calculated
Next
type3
 Type 3.Continuously Variable
Transmission
• A continuously variable transmission (CVT) has a gear
ratio that can be varied continuously within a certain
range, thus providing an infinity of gear ratios.
• This continuous variation allows for the matching of
virtually any engine speed and torque to any wheel
speed and torque.
• It is therefore possible to achieve an ideal torque–
speed profile (constant power profile)because any
engine power output to the transmission can be
applied at any speed to the wheels.
• The commonly used CVT in automobiles uses a
pulley and belt assembly.
• One pulley is connected to the engine shaft,
while the other is connected to the output shaft.
• The belt links the two pulleys. The distance
between the two half pulleys can be varied, thus
varying the effective diameter on which the belt
grips. The transmission ratio is a function of the
two effective diameters:
• where D1 and D2 are the effective diameters of the output
pulley and input pulley, respectively.
• Until recently, this implementation was affected by the
limited belt–pulley adhesive contact.
• The design has been improved by the use of metallic belts
that provide better solidity and improved contact.
• Furthermore, an interesting concept has been developed
and is being used by Nissan. This concept uses three
friction gears: one is connected to the engine shaft,
another to the output shaft, while the third gear grips on
the particular profile of the other two gears. It can be
rotated to grip on different effective diameters, therefore
achieving a variable gear ratio.
General explanation
A variable displacement pump is a device that converts mechanical energy to hydraulic en
The displacement, or amount of fluid pumped per revolution of the pump's input shaft
can be varied while the pump is running.
 5 and 10 mark questions
• Explain the conceptual basics of automobile
power train(5)
• Explain power plant characteristic of electric and
go saline engine(10)
• What is hydro dynamic transmission .explain with
suitable diagram(5)
• What Is continuously variable transmission
explain with suitable diagram(5)
• Explain transmission characteristic with suitable
diagram(10)
Topic finished
 Autonomous Vehicles:
• Levels of automation, significance & effects of
automation in vehicles (1 hr)
• An autonomous vehicle, or a driverless
vehicle, is one that is able to operate itself
and perform necessary functions without any
human intervention, through ability to sense
its surroundings.
• An autonomous vehicle utilises a fully
automated driving system in order to allow
the vehicle to respond to external conditions
that a human driver would manage.
 What are the 6 Levels of
Autonomous Vehicles?
• There are six different levels of automation and, as the levels
increase, the extent of the driverless car’s independence
regarding operation control increases.
• At level 0, the car has no control over its operation and the
human driver does all of the driving.
• At level 1, the vehicle’s ADAS (advanced driver assistance
system) has the ability to support the driver with either
steering or accelerating and braking.
• At level 2, the ADAS can oversee steering and accelerating
and braking in some conditions, although the human driver is
required to continue paying complete attention to the driving
environment throughout the journey, while also performing
the remainder of the necessary tasks
• At level 3, the ADS (advanced driving system) can perform all parts of the
driving task in some conditions, but the human driver is required to be
able to regain control when requested to do so by the ADS. In the
remaining conditions, the human driver executes the necessary tasks.
• At level 4, the vehicle’s ADS is able to perform all driving tasks
independently in certain conditions in which human attention is not
required.
• Finally, level 5 involves full automation whereby the vehicle’s ADS is able
to perform all tasks in all conditions, and no driving assistance is required
from the human driver. This full automation will be enabled by the
application of 5G technology, which will allow vehicles to communicate
not just with one another, but also with traffic lights, signage and even the
roads themselves.
• One of the aspects of the vehicle technology used in
automated vehicles is ACC, or adaptive cruise control. This
system is able to adjust the vehicle’s speed automatically to
ensure that it maintains a safe distance from the vehicles in
front of it. This function relies on information obtained using
sensors on the vehicle and allows the car to perform tasks
such as brake when it senses that it is approaching any
vehicles ahead. This information is then processed and the
appropriate instructions are sent to actuators in the vehicle,
which control the responsive actions of the car such as
steering, acceleration and braking. Highly automated vehicles
with fully automated speed control are able to respond to
signals from traffic lights and other such non-vehicular
activities.
 effects of Autonomous Vehicles
• 1. REDUCED ACCIDENTS
• "Self-driving cars have the potential in the
future to reduce deaths and injuries from car
crashes, particularly those that result from
driver distraction,
• REDUCED TRAFFIC CONGESTION
• Even decreasing the number of accidents
could reduce congestion, because up to 25%
of congestion is caused by traffic incidents
• REDUCED CO2 EMISSIONS
• Since software will drive the car, the modern
vehicle can now be programmed to reduce
emissions to the maximum extent possible.
The transition to the new-age cars is expected
to contribute to a 60% fall in emissions.“
• INCREASED LANE CAPACITY
• 360° vision. Thanks to high-precision
technology, autonomous vehicles possess the
ability to view the environment in a 360°
range, twice as much as humans, who have a
viewing angle of only 180° horizontally.
• Access to the disabled and people with
reduced mobility. Thanks to the fact that the
automobile will be autonomous and will
require practically no human interaction for its
operation, even people with visual or hearing
disabilities will be able to have one, i.e., they
will become inclusive
 Topic over
• what are the factors influenced in the vehicle performance. Explain with suitable example(10)
• explain tractive force(5)
• explain Grade resistance, how to measure gread resistance with suitable example(5)
• .how to calculate the Resistance of vehicle(3)
• derive the concept of Rolling Resistance(3)
• how Aerodynamic Drag affect the vehicle resistance(4)
• what is Shape drag. draw the various vehicle shape with respect to drag coefficient(5)
• Draw and explain Tractive effort of electric motored powered vehicle transmission and its
resistance(5)
• .draw and explain the Tractive effort of a gasoline engine-powered vehicle with multispeed
transmission and its resistance(5)
• .explain the term Grading Resistance(3)
• explain the General Description of tire rolling resistance (3)
• explain the .Resistance of vehicle with suitable diagram(5)
• how to calculate Acceleration Performance(3)
• Explain the various level of autonomous vehicle system
• Explain the various transmission characteristic