Toyota has developed various hybrid and alternative fuel vehicle technologies to improve fuel efficiency and energy security. These include hybrid systems combining an internal combustion engine with electric motors, as well as electric and fuel cell vehicles. The Toyota Hybrid System was introduced in the Prius in 1997 and combines a small gasoline engine with electric motor-generators through a power-split device, allowing the car to be powered by the engine or motor alone or both working in parallel. The system is controlled by a computer to optimize efficiency.

2.  Toyota has been actively developing various new technologies from the
perspective of achieving energy security and diversifying energy sources,
which is necessitated by the dwindling supply of petroleum resources.
 Lean-burn gasoline engines
 Direct injection
 Gasoline engines
 Common rail direct-injection diesel engines
 Compressed natural gas (CNG) driven engines
 Electric vehicles (EV) that use motors for the driving source
 Hybrid vehicles (HV)
 Fuel cell hybrid vehicles (FCHV)

3.  Fusion between an internal combustion engine and electric motor—
achieving different functions through different power combinations.
 There are various types of hybrid systems, the two renowned ones are:
 A system that combines two motive power sources, such as an internal
combustion engine and an electric motor.
 A fuel cell hybrid vehicles (FCHV) that use fuel cells (FC) to generate
electricity based on a chemical reaction between hydrogen and the oxygen in
the air and that supply this electricity to electric motors to produce driving
power.
 The three types of hybrid systems being used in the market these days are:
Series Hybrid system, Parallel Hybrid system, Series Parallel Hybrid System.

4.  In January 1997,Toyota declared the start of theToyota Eco Project.
Then, in March of the same year,Toyota announced the completion
of a new power train called theToyota Hybrid System (THS) for use
in passenger vehicles.
 THS was installed in the passenger vehicle Prius, which was
introduced in December 19
 THS has continued to evolve and the various models introduced are:
THS-C, which combinesTHS with CVT,THS-M (a mild hybrid
system).
 Building on the ecology-focusedTHS,Toyota has developed the
concept of Hybrid Synergy Drive. Based on this concept,Toyota has
developed a new-generationToyota hybrid system calledTHS II.

5.  HSD replaces a normal geared transmission with an electromechanical
system.
 All car powertrains drive a driveshaft that turns the drive wheels of the
car.
 HSD replaces the gear box, alternator and starter motor with a pair of :
 electrical motor-generators (MG), a computerized shunt system to
control them, a mechanical power splitter that acts as a second
differential, and a battery pack that serves as an energy reservoir.
 An HSD car cannot operate without the computer and MG2, though in
principle it could operate while missing the gasoline engine.
 In practice, HSD cars can be driven several kilometers without gasoline,
as an emergency measure to reach a gas station.

6.  The power train of the Prius II consists of:
 A 1.5 liter 4 cylinder gasoline engine
 A special generator MG1 mounted to the back of the engine which
doubles as a starter motor.
 A planetary gear set that connects the generator and the gasoline
engine to the drive wheels
 An electric motor MG2 also connected to the drive wheels
 A HV Ni-MH battery pack with a rated voltage of 273,6V.

7.  The Prius has an internal
combustion engine (ICE) which is
unusually small for a car of this
size (1300 kg).
 The possibility of using a small
engine in a hybrid vehicle is called
"engine downsizing".
 The engine uses the Atkinson
cycle, rather than the usual Otto
cycle.
 The crankshaft is offset from the
cylinder axes so that during the
combustion stroke the force from
the piston is transmitted to the
crankshaft through a straight
rather than tilted connecting rod.
 The engine power is 70 hp at 4500
rpm.

8.  Toyota uses prismatic Ni Metal
Hydride modules from Panasonic.
 Each module consists of six 1,2V
cells connected in series.
 The module has a nominal voltage
of 7,2V, capacity of 6,5 Ah, weighs
1,04 kg.
 38 prismatic NiMH modules
connected in series are used in the
battery stack.
 The complete battery pack consists
of the battery stack, enclosure for
structural support and airflow,
battery electronic control
unit/monitor, relays and safety
switch. It weighs around 53 kg.
 The maximum current of the battery
is 80 amps discharge and 50 amps
charge.

9.  Power split device is the heart
of a hybrid system.
 It hooks the gasoline engine,
generator and electric motor
together.
 It allows the car to run as a
parallel hybrid-the electric
motor alone can drive the car.
 It can also run the car as a
series hybrid-meaning the
car can drive on the gasoline
engine alone.

10.  A series parallel hybrid system is
used in theToyota Prius.
 It combines the gasoline engine
and the electric motor to get the
maximum benefits of both.
 The car can either run on the
gasoline engine or the car can
run on the electrical battery. Or
they can both run parallel to
each other.

14.  The HYBRID SYNERGY DRIVE computer oversees operation of the entire
system, determining which engine/MG should be running, or if both
should be in use, or shutting off the internal combustion engine when the
electric motor is sufficient to provide the power.
 At start-off/low-speeds, HSD runs the car on the electric motor only,
since the internal combustion engine does not perform efficiently.

18. Following are some of the reasons why hybrid cars are being
called highly fuel efficient.
 They can recover energy and store it in the battery
 Sometimes shut off the engine
 Use advanced aerodynamics to reduce drag
 Use low-rolling resistance tires
 Use lightweight materials