OVERVIEW OF POWERTRAIN

Mr. B.Harishbabu

TRANSPORTATION/MOBILITY

Transportation/Mobility is a vital to modern economy Transport of People Transport of goods and produce

People get accustomed to the ability to travel. Mobility is must, but not at the cost of environment

EMISSION REQUIREMENTS

1975 1980 1985 1990 1995 2000 2005 20100.01

0.1

1

Euro 5

Euro 4

1975

1977

19811994 TLEV

1997-2003 ULEV

2004 SULEV2

NO

x(g/

mile

)

Starting year of implementation

Euro 3

1975 1980 1985 1990 1995 2000 2005 2010

0.01

0.1

1

Euro 4

Euro 5

19771975

1981 1994 US

1994 TLEV

1997 TLEV

1997-2003 ULEV

2004 SULEV2

NM

OG

(g/m

ile)

Starting year of implementation

Euro 3

(Gasoline engines)

Historic trend: Factor of 10 reduction every 15 years

ENERGY SOURCE Vehicles need to carry source of energy on

board Hydrocarbons are unparalleled in terms of

energy density For example, look at refueling of gasoline

~10 Liters in 1 minutes (~0.125 Kg/sec) Corresponding energy flow = 0.125 Kg/sec x 44 MJ/Kg = 5.5 Mega Watts

Liquid hydrocarbons !

TRANSPORTATION ENERGY UTILITY(DOES NOT INCLUDE MILITARY TRANSPORTATION)

Source: US Dept. of Energy

2003

1970 1980 1990 2000 20100

5

10

15

20

25

30

Ene

rgy

use

(x10

15 B

ThU

)

Year

Passenger cars

Light trucks

Heavytrucks

Non-Highway

USA

INDUSTRY INERTIA Capital Penetration

Need for Budget / Financial Approvals

Technology PenetrationTakes time to develop and implementExample: Automotive Powertrain

a. Incremental changes: Design needs to be completed 3-4 years before production

b. Significant changes: Add 5-10 years of development time to (a)

c. Drastic changes: Add 10 to 15 years to (a)d. Radical changes: Add ? years to (a)

Market penetration

THERMODYNAMIC PRINCIPLES REVIEW Thermodynamics is the study of heat related to matter

in motion. Heat engine is a mechanical device which convert the

heat energy into mechanical work

7

Engine11

. ,TQ 22

. ,TQ

.W

REVERSIBLE PROCESS Reversible process is the rate of generation of entropy

is always zero (also named as isentropic process). Typical reversible processes are

· Constant pressure process · Constant temperature process· Constant volume process · Adiabatic process

Reversible process can be approximated by a polytropic process,

pVn = Constant

where n is the polytropic indexn = 0 constant pressure processn = 1 constant temperature processn = adiabatic processn = constant volume process

8

n=0

n=1

n= n=

V

P

WORK If a system exists in which a force at the boundary of the

system is moved through a distance, then work is done by or on the system.

The work done by the system isdW = pAdx = pdV

The total work done 9

2

1

2

1pdVdWW

ENERGY Energy is the capacity a body or substance possesses

which can result in the performance of work. Heat is the energy transferred between one body and

another resulted from the temperature difference.

and

Internal Energy is the energy content resultant from the consideration of the temperature of a substance.

Enthalpy- First Law of Thermodynamics: dq=du+dw=du+pdv=d(u+pv)- Enthalpy is defined as: h=u+pv

10

dTpcq dTvcq

THERMODYNAMIC GAS CYCLESOtto Cycle

1 – 2: isentropic compression2 – 3: constant-volume heat addition3 – 4: isentropic expansion4 – 1: constant-volume heat rejection

Compression ratio

Heat addition Qin=mcv(T3-T2) Heat rejection Qout=mcv(T4-T1)

11

1

4

3

2

V

p

34

21

VV

VV

r

Isentropic compression Perfect gas pV = mRT Isentropic process pV = constant

Isentropic expansion

Cycle efficiency

12

rpp

12 1

12 rT

T

rpp 1

3

411

3

4

rTT

inQoutQinQ

inQoutW

Otto

111 r

DIESEL CYCLE1 – 2: isentropic compression2 – 3: constant-pressure heat addition3 – 4: isentropic expansion4 – 1: constant-volume heat rejection

Compression ratio

Heat addition Qin=mcp(T3-T2)

Heat rejection Qout=mcp(T4-T1)

Cut-off ratio

Cycle efficiency 13

34

21

VV

VV

r

1

4

3 2

V

p

23

VV

11

111

rDiesel

DUAL CYCLE

1 – 2: isentropic compression2 – 2a: constant-volume heat addition2a – 3: constant-pressure heat addition3 – 4: isentropic expansion4 – 1: constant-volume heat rejection

Heat addition Qin=mcv(T2a-T2)+mcp(T3-T2a)

Heat rejection Qout=mcp(T4-T1)

Cut-off ratio

Constant volume heat addition pressure ratio

Cycle efficiency 14

1

4

3

2

V

p 2a

aVV

23

23

pp

11

1111

rDual

FUNCTIONAL REQUIREMENTS OF ENGINE

15

•Power•Torque curve•Speed range•Duty cycle•Weight/space•Reliability •Durability•Cost

•Fuel economy•Emissions•Noise•Power takeoff•Flexibility•Serviceability•Recycling•Other

HEAT ENGINE CLASSIFICATION

16

Engines

Internal Combustion Engines External Combustion Engines

Spark Ignition Engines Compression Ignition Engines

Carburettor CFI PFI GDI IDI DI

EXTERNAL COMBUSTION ENGINES

Stirling Engine

17

INTERNAL COMBUSTION ENGINES

18Figure 3-3 Two stroke engine

Two-stroke Engines

FOUR-STROKE ENGINES

19

SIZES OF ENGINES

The Most Powerful Diesel Engine in the World!

Some facts on the 14 cylinder version: Total engine weight: 2300 tons  (The crankshaft alone weighs 300 tons.) Length:89 feet Height:44 feet Maximum power: 108,920 hp at 102 rpm  Maximum torque: 5,608,312 lb/ft at 102rpm 

20

A 2-stroke medium sized “diesel” engine. The compression ratio adjusting screw can be seen at the top pf the of the cylinder head.

Millimeter-scale rotary MEMS.

INTRODUCTION TO SI ENGINE

In traditional SI engines, the fuel and air are mixed together in the intake system using a low pressure (circa 2 to 3 bar) fuel injection system (carburettors no longer used).

Fuel injection system is normally multi-point port injection, which means that there is one fuel injector (sometimes two) in each inlet port.

Multi-point injectors normally inject fuel onto the back of the closed inlet valve using sequential timing with the required amount of fuel quantity being updated by the ECU every engine event.

21

Air Fuel Mixture

Air/fuel Ratio, AFR The AFR has a very significant effect on the power output, thermal

efficiency and exhaust emissions and has to be controlled precisely over the whole operating range.

All modern engines use an electronic control unit (ECU) and various sensors and actuators to control the AFR.

The air to fuel ratio by mass (AFR) is typically 14.3:1 for gasoline fuels.

22

Spark plug and ignition coil. Distributor and distributorless systems

Combustion Ignition

Instead of one main coil, distributorless ignitions have a coil for each spark plug, located directly on the spark plug itself

Load Control Throttle plate

Figure 1.19 Idealised SI engine flame propagation

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Spark Ignition Combustion

Homogeneous mixture of air, fuel and residual gas.

Spark ignition shortly before TDC. Flame propagation. The combustion typically takes 50

degrees of crank angle The products of combustion: N2, CO2,

H2O vapour, O2, CO, H2, HCs, NOx. Cycle to cycle variation knock

24

INTRODUCTION TO CI ENGINE Air only is drawn into the cylinder during the intake stroke Load control is achieved by adjusting the quantity of fuel injected directly into cylinder The in-cylinder charge is stratified Peak cylinder pressure is typically limited to 150 bar

25

General

Fuel Injection Starts just before TDC and continuous until just after TDC.

Fuel quantity injected dependents on the power output required.

Line pressure between 400 and 1500 bar In-line pump (large diesel engines only), Distributor/rotary pump (traditionally used for car engines), Unit-injector Common-rail (very recent system). Common-rail systems are set to displace conventional

jerk pump systems in the near future.

A diesel engine built by MAN AG in 1906

Ignition delay Diesel knock High Cetane number required

26

Combustion ignition

Combustion control

Diesel engines have changed considerably over the last 10 years, the main design trends being:

Use of DI rather IDI (DI is approximately 20% more fuel efficient)

Full electronic control (essential for emission control, economy and refinement)

Higher fuel injection pressures up to 1500 bar (improved emissions)

Use of common rail injection (much improved control) Installation of two-spring injectors (noise reduction) Use of 4 valves per cylinder

(improved combustion and emissions) Increased used of turbochargers and inter-coolers

(performance and emissions) Use of oxidation catalysts 27

Improvements in Design:

COMPARISON OF SI AND CI ENGINES SI engine

(traditional) CI engine

Fuel type Petrol, gasoline, natural gas, methanol, etc.

Diesel oil, vegetable oils, MTBE, etc.

Fuel requirement

High Octane number High Cetane number

Ignition Electrical discharge Compression temperature Compression ratio

Typically 8.0 to 12.0:1

Typically 12.0 to 24.0:1

Fuel system Low pressure fuel injection

High pressure fuel injection

Load control Quantity of govern by throttle

Quality govern by AFR

Mixture in cylinder

Homogeneous Stratified

Inlet charge Seldom turbocharged Usually turbocharged Typical AFR range

12.0 to 18.0:1 20.0 to 70.0:1

Development trends

Direct injection Common-rail, 4 valves, full electronic control

Main advantages

High specific power,

low capital cost

High thermal efficiency, low CO, HC emissions

Main issues CO2 emissions, poor part load

efficiency

NOx, particulate emissions, noise

Emission control

EGR, 3-way catalyst

EGR, injection timing, oxidation catalyst

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CONVERGENCE OF S.I. AND C.I. TECHNOLOGY

Attribute

Fuel DeliveryAir DeliveryValve TrainEGRCompression Ratio

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S.I.

PFI→D.I.N. Aspirated→Turbo4V DOHCYesIncreasing

C.I.

D.I.Turbo4V DOHCYesDecreasing

ENERGY SOURCE/VEHICLE SYSTEM

30Fuel-Cell ElectricHydrogen

ShiftReaction

Plug-In Hybrid ICE

Electric VehicleElectricity

Heat

Renewables(Solar, Wind, Hydro)

Nuclear

EnergyEnergyCarrierCarrier

PropulsionPropulsionSystemSystemConversionConversion

Ele

ctri

ficat

ion

EnergyEnergyResourceResource

ICE Hybrid

Conventional ICE:Gasoline / Diesel Liquid

Fuels

Petroleum FuelsOil(Conventional)

Oil(Non-Conventional) Synthetic Fuels (XTL)

SyngasCO, H2

FischerTropsch

Coal

Natural Gas

1st and 2nd Generation Biofuels

Biomass

Cri

tical

Dep

ende

ncy

on B

atte

ry T

echn

olog

y

Source: Shell Group

“WELL TO WHEELS” ELECTRIC POWER FUEL CYCLE

31

Coal MineUnit Train

Loader Electric Vehicle

Transmission Lines

Coal-Fired Boiler/Steam Turbine/Generator

Charger/Service Station

(Conventional Fuel Mix: 50% Coal, 19% Gas, 3% Oil, 19% Nuclear, 9% Non-Fossil Fuel)

WELL TO WHEELS EFFICIENCY

32

Source: Argonne National Labs, GM, industry sources

33

Relative CO2 emissions （ Gasoline Eng. = 1 ）-1.0 -0.5 0 0.5 1 1.5

Otto Engine

DieselEngine

GasolineGasoline

Gasoline-HVGasoline-HV

CNG(LNG)CNG(LNG)

DieselDiesel

FTD(NG)FTD(NG)

FTDFTD(Biomass)(Biomass)

BDF(Rapeseed)BDF(Rapeseed)

Ethanol(Sugarcane)Ethanol(Sugarcane)

HH22 (NG, on-site) (NG, on-site)

Well to Tank CO2(WTT)

Tank to Wheel CO2(TTW)@ Japanese 10.15 mode

FC: H2

HH22 (Biomass, on-site) (Biomass, on-site)

WELL TO WHEELS CO2 EMISSIONS

FTD(Coal)FTD(Coal)

Ethanol Ethanol (Iogen)

HH22 (electrolysis) (electrolysis)

(Cellulose)(Cellulose)

Diesel Engine

OttoEngine

Synthetic Fuel

Source: EUCAR EC-JRC 2006

ENERGY PATHWAY FOR A TYPICAL PASSENGER CARURBAN (HIGHWAY) FIGURES

Standby17.2 (3.6) %

Accessories2.2 (1.5) %

Engine Losses62.4 (69.2) %

Braking5.8 (2.2) %

Kinetic

Rolling4.2 (7.1) %

Aero2.8 (10.9) %

Drive Line Losses5.6 (5.4) %

EngineFuel

Energy100%

Drive Line18.2%(25.6%)

12.8%(20.2%)

(Source: Partnership for a New Generation Vehicle (PNGV) Program Plan, July 1994)

Energy sinkEnergy conversion and transmission

EFFICIENCY IMPROVEMENTS

Standby17.2 (3.6) %

Accessories2.2 (1.5) %

Engine Losses62.4 (69.2) %

Braking5.8 (2.2) %

Kinetic

Rolling4.2 (7.1) %

Aero2.8 (10.9) %

Drive Line Losses5.6 (5.4) %

Engine

FuelEnergy100%

Drive Line18.2%(25.6%)

12.8%(20.2%)

Engine opportunity

On demand accessories

Better transmission

Better aerodynamics

Better tires, lower rolling resistance

Vehicle engineering

Regenerative braking

Engine stop and go

Energy storage element

ENGINE OPTIONSEngine Attributes Drawbacks

SI Engine Well developed Poor sfc at part load

Turbo-charged Diesel Well developed, good sfc

Cost; emissions

Hybrid Optimized operating range; regeneration

Cost; battery

Gasoline HCCI On going research efforts

Diesel HCCI

STATE OF ART – ENGINE SYSTEM

37

Other cutting edge design considerations – peak cylinder pressure, fuel injection pressure, piston speed, valve seating velocity, exhaust temperature limit, etc.

SUMMARY Powertrain is a complex but interesting

thermodynamic application. Supremacy over Powertrain Engineering will

lead to power in your hand. There is a convergence of C.I. and S.I. Engine

technologies. Alternatives must be compared on a “Well to

Wheels” basis. Liquid Hydrocarbon fuels: The dominant fuel

source for many years to come. Hybridization / Electrification of engines will

continue to increase.

TRENDS IN POWERTRAIN 2007

38

THANK YOU!

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