Toyota’s Hybrid Technology
Yoshihiro Onomura
General Manager, Planning & Administration Dept.
Hybrid Vehicle Engineering Management Div.
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1. Birth of the world’s first mass
produced hybrid: the Prius
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The Challenge of car-making for the 21st century: Prius development 3
Toyota started development of Prius in 1993, autumn
The theme that was given to the project team at that time:
• Create the 21st century car
• Change the vehicle development method
Project name: “G21”
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The Challenge of car-making for the 21st century: Prius development
The mission of Prius was to create an entirely new concept vehicle
to meet 21st century needs = outstanding fuel economy
Maintain or enhance good usability or comfort of
conventional vehicles, but also simultaneously
respond to the Challenges of motorized society in
the 21st century
Overcome energy resources / environmental
issues
Realize outstanding fuel economy
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The Challenge of car-making for the 21st century: Prius development
Prius achieved far better fuel economy than original target
Original target
Ideal target
1.5 times better
fuel economy
(Extension of existing technology)
Target too low to develop
the vehicle for the future
2 times better
fuel economy
Not just do “What we can”,
but do “What we should”
Mass production of the hybrid vehicle
Prius
Conventional
vehicle 1.5L
(Gasoline)
28.0km/L
14.0km/L
(Japanese 10-15 test
mode)
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The Challenge of car-making for the 21st century: Prius development
Dec. 1997 Sales of Prius had Begun
World’s first mass produced hybrid vehicle
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2. What are Hybrids?
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Feature of Toyota’s Hybrid Vehicles
Hybrid vehicles have two power sources; Gasoline engine
and electric motor which bring about greater efficiency
Gasoline engine
Gasoline engine vehicle
Electric motor
Electric vehicle
Gasoline engine + Electric motor
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Feature of Toyota’s Hybrid Vehicles
By combining the benefits of gasoline engines and
electric motors, hybrid vehicles offer excellent driving performance
and eco-friendliness
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Feature of Toyota’s Hybrid Vehicles
When Hybrid vehicles are in EV mode, only the electric motor works
and therefore, no CO2 emissions.
No CO2 emissions
while EV mode
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Feature of Toyota’s Hybrid Vehicles
Also, hybrid vehicles save energy recovered from braking
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Feature of Toyota’s Hybrid Vehicles
HVs use two or more distinctive types of power to
enhance fuel efficiency and environmental performance
through recovery and re-using of energy
First Prius (1997) :
Gas Station
(1) The world’s first mass
Battery
Motor
produced HV
(2) Power sources – the
Engine
Fuel Tank
internal combustion
engine and electric motor
(3) Battery is the power buffer which allows regenerated
power during braking to be re-used
(4) Achieve high level of fuel efficiency and low-emissions
with 2 power sources and battery
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Driving energy in conventional vehicles
Energy needed for driving is often not in the high-efficiency area
+
Energy
Energy needed for driving vehicle
Engine High-efficiency
operating area
Constant running
Stop
Time
Deceleration
-
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Energy management of Toyota’s Hybrid System
In hybrid vehicles, battery supports engine for the less-efficiency
operation area, and also store energy for less energy consuming drive
Battery
+
Driving Energy
Supply necessary
energy
3
Surplus Energy
Storage
High-efficiency
operating area
Energy
2
1
Engine power
Re-generating
Energy
4
(maximum efficiency)
Engine stop
STOP
START
Full throttle
Eng stop
Battery
Battery+Eng
Constant
speed
Braking
Eng
Battery
charge
5
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How Toyota’s Hybrid System works
When starting and light-load driving, electric motor drives
the wheels by using electricity from the battery
Starting and light-load driving
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How Toyota’s Hybrid System works
When normal driving, the engine power is split into 2 portions,
1) for driving the wheels,
2) for feeding generator/motor to supplement engine power
Excess electricity during light-load driving is charged to battery
Normal driving
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How Toyota’s Hybrid System works
When in full acceleration mode, battery supplies
more power to drive the electric motor.
Full acceleration
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How Toyota’s Hybrid System works
When decelerating and braking, regenerative braking recharges
the electricity from motor to battery
Decelerating and braking
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How Toyota’s Hybrid System works
The amount of charged electricity has reduced,
the engine drives the generator to recharge the battery
Battery-charging
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Why Toyota’s Hybrid System is fuel efficient
Toyota’s Hybrid technology realizes high fuel efficiency
compared to gasoline engine cars
Fuel efficiency improvement
City Mode
Vehicle: Prius-class model
2
Regenerative braking
Idling stop
Engine use in fuel efficient area
・ EV driving mode (start driving, light-load driving)
・ Engine use in fuel efficient area (normal driving)
Engine improvement
1
Advantages of
hybrid vehicle
0
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Gasoline AT
Gasoline HV
Why Toyota’s Hybrid System is fuel efficient
Toyota’s hybrid vehicles are “strong hybrid” vehicles
that combine the use of a high efficient gasoline engine
and a high output electric motor/generator.
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Why Toyota’s Hybrid System is fuel efficient
The difference between Strong HV and Mild HV is that
Strong HV has the EV drive function
Classification by function of hybrid systems
Hybrid
Improvement of
fuel efficiency
Strong
EV Drive
Mild
Motor Assist
Regenerative Braking
Engine Stop
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High fuel efficiency
Better
Strong HV fuel efficiency is much better than that of Mild HV
(Japan Crown HV) 23
High fuel efficiency and better cost performance
Strong Hybrids are relatively more costly,
but have high fuel efficiency and are more cost effective
Fuel Efficiency
high
Hybrid
Cost (Price)
high
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Low emissions: Carbon dioxide (CO2)
Hybrid vehicles can contribute to the reduction of CO2 emission
High
Gasoline
CO2 emission
(g/km)
Diesel
Gasoline HV
LS600h
RX450h
Prius
GS450h
Camry HV
Yaris HV
Prius PHV
Vehicle weight (tons)
Heavy
EC mode
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Low emissions: Nitrogen oxide (NOx), Carbon dioxide (CO2)
HVs manage both lower emissions(NOx) and lower CO2
CO2 (g/km)
*New European Driving Cycle
Gasoline
Diesel
Low CO2
Tank to wheel
Europe C-segment (NEDC* mode)
HV
Clean
Tank to wheel
NOx (g/km)
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Low emissions: Hydrocarbon (HC)
The more HVs there are on the road, the atmosphere becomes
cleaner
Cleaner air*
HC concentration (ppm)
Polluted air
Roadside HC concentration
Vehicle emission
HC concentration
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*Concentration levels of HC in the air in urban areas is reduced.
High driving performance
HVs realize the dual functions of
high driving performance and fuel efficiency
JC08 Mode Fuel Efficiency (km/L)
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☆ 4th Prius (1.8L)
40
35
Better
30
25
Quick
3rd Prius (1.8L)
2nd Prius (1.5L)
Other HV(1.3L)
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Premio 2.0L
15
Camry 2.4L
10
5
Collora 1.5L
3
3.5
4
4.5
5
5.5
6
Mid range acceleration 40-70km/h (sec)
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Benefit of Toyota’s HV
In addition to high fuel efficiency and low emissions,
hybrid vehicles have strong power and quietness as characteristics
High fuel efficiency
Low emissions
Power
Quietness
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Benefit of Toyota’s HV: Power
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Benefit of Toyota’s HV: Quietness
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3. Evolution in the
Fourth-generation Prius
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Fourth-Generation Prius: Fuel efficiency improvement
Prius has improved its fuel efficiency over the generations
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Fourth-Generation Prius: Fuel efficiency improvement
25.2% improvement was made from previous Prius
and powertrain has contributed to 18.2% of improvement.
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Fourth-Generation Prius: Fuel efficiency improvement
Engine efficiency improvement and reduction in energy loss of
HV electric units are the key improvements in powertrain.
1. Engine efficiency
improvement
~Advancement of TNGA
Engine~
2. Drastic energy loss
reduction of HV
electric units
3. Synergy effect
between 1. and 2.
as system
fig.Breakdown of powertrain
fuel efficiency improvement
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Fourth-Generation Prius: Advance fuel efficiency technology
To achieve the high fuel efficiency, not only the HV system,
but aerodynamics has been improved as well
<Low fuel consumption>
■Improved 2ZR-FXE engine
・Maximum thermal efficiency of 40%
■New Hybrid System development
■World-class aerodynamic performance
・Cd*:0.24 (Camry : 0.28)
・Flat under floor
・Grill shutter
*Drag coefficient
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4. Reliability Evaluation
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Durability and safety of HVs
Many taxis use HVs
because of their durability and fuel efficiency
In Austria
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Durability and safety of HVs
Many used HVs are imported into Sri Lanka, Myanmar, Mongolia,
etc. as second hand vehicles which shows long life of vehicles
Myanmar
Sri Lanka
Mongolia
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Batteries Durability Management
For good durability, hybrid electric vehicles
control SOC and temperature of battery
SOC (%)
Range of the State of charge (SOC)
Cellular phone
HV
500,000km
Worse (Deterioration)
Battery capacity
Ni-MH Battery Durability in Market
No Deterioration
Up to 500,000km
Taxis
100,000
200,000
300,000
400,000
Running distance (km)
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Example of reliability evaluation
Hybrid vehicles are evaluated with
all the same reliability test as conventional vehicles
transformation
Strength
fatigue
Multi spindle bench
Rough road
・
・
water
Specific
environment
temperature
Low temp.
room
Floodway
・
Electromagnetic
Interference
immunity
emission
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Anechoic chamber
Example of the reliability evaluation of battery
Batteries unique to Hybrid vehicles are evaluated
through many reliability tests
1. Charge and discharge durability
Inside of thermostat room
2. Durability vibration
vibration machine
with thermostat
room
controller
wiring condition
3. Inspect collected parts from the market
4. Battery control management
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Laboratory evaluation
Ensuring market suitability by conducting battery evaluation tests;
simulating the real-world environment
Charge and discharge controller:
simulate actual current
current(A)
Temperature and humidity room:
simulate actual environment
(ex) simulate
mountain drive
and others
time(second)
Inside of temperature and
humidity testing room
discharge
Power
supply
battery
charge
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Vibration test simulated uneven rough road conditions
Toyota conducts vibration tests on batteries
by simulating the various road conditions around the world
Triaxial vibration machine
with thermostat room
Controller
Inside of the thermostat room
★evaluate functional quality and damage
by simulating vibration and temperature
of actual vehicle
Vibration machine
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Battery drop evaluation
Battery test example: Drop battery from great heights
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Battery drop evaluation
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Water leak evaluation
Battery test example: Water immersion
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Water leak evaluation
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TODAY for TOMORROW
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