overview of powertrain
TRANSCRIPT
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
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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
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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)
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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
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•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
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Engines
Internal Combustion Engines External Combustion Engines
Spark Ignition Engines Compression Ignition Engines
Carburettor CFI PFI GDI IDI DI
EXTERNAL COMBUSTION ENGINES
Stirling Engine
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INTERNAL COMBUSTION ENGINES
18Figure 3-3 Two stroke engine
Two-stroke Engines
FOUR-STROKE ENGINES
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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
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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.
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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.
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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
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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
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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
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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
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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
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Source: Argonne National Labs, GM, industry sources
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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
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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
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THANK YOU!
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