DETAILED ANALYSIS OF THE TOYOTA PRIUS ENGINE

VARIOUS ENGINES DEVELOPED BY TOYOTA 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)

WHAT IS A HYBRID SYSTEM? 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.

TOYOTA HYBRID SYSTEM In January 1997, Toyota declared the start of the Toyota

Eco Project. Then, in March of the same year, Toyota announced the completion of a new power train called the Toyota 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 combines THS with CVT, THS-M (a mild hybrid system).

Building on the ecology-focused THS, Toyota has developed the concept of Hybrid Synergy Drive. Based on this concept, Toyota has developed a new-generation Toyota hybrid system called THS II.

HYBRID SYNERGY DRIVE

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.

POWER ELECTRONICS OF TOYOTA PRIUS

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 273,6

V.

INTERNAL COMBUSTION ENGINE 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.

THE TOYOTA PRIUS BATTERY PACK Toyota uses prismatic Ni

Metal Hydride modules from Panasonic.

Each module consists of six 1,2 V cells connected in series.

The module has a nominal voltage of 7,2 V, 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.

POWER SPLIT DEVICE 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.

SERIES PARALLEL HYBRID SYSTEM

A series parallel hybrid system is used in the Toyota 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.

TOYOTA PRIUS ENGINE

PLANETARY GEAR SET

HOW THE PGS WORKS

PRIUS DRIVE PHASES OF OPERATION

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.

PHASE OF OPERATION WHILE CRUISING

WHILE ACCELARATING

WHILE DECELARATING OR BRAKING

FUEL ECONOMY

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

THANKYOU!

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