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A New Type Car -- Hybrid Electric Vehicle

With

skyrocketing

fuel

prices

and

changes

in

weather

patterns,

many

car

manufacturers claimed to develop the kind of vehicles that will increase the mileage

and

reduce

the

emissions.

Hybrid

car

is

a

kind

of

vehicle

which

can

meet

above

requirements. A hybrid car features a small fuel-efficient gas engine combined with an

electric motor that assists the engine.

The

reasons

of

building

such

a

complicated

machine

are

twofold:

to

reduce

tailpipe

emissions

and

to

improve

mileage.

Firstly,

hybrid

cars

are

good

for

the

environment. They can reduce smog by 90 percent and they use far less gasoline than

conventional cars. Meanwhile, hybrid cars burn less gasoline per mile, so they release

fewer

greenhouse

gases.

Secondly,

hybrid

cars

are

economical.

Hybrid

cars,

which

run on gas and electricity, can get up to 55 to 60 miles per gallon in city driving, while

a

typical

SUV

might

use

three

times

as

much

gas

for

the

same

distance!

There

are

three reasons can mainly account for that: 1) Hybrid engines are much smaller than

those on conventional cars. A hybrid car engine is to accommodate the 99% of driving

time when a car is not going up hills or accelerating quickly. When extra acceleration

power is needed, it relies on the battery to provide additional force. 2) Hybrid gasoline

engine can shut off when the car is stopped and run off their electric motor and battery.

3)

Hybrid

cars

often

recover

braking

energy.

Electric

motors

could

take

the

lost

kinetic

energy

in

braking

and

use

it

to

charge

the

battery.

Furthermore,

hybrids

are

better than all-electric cars because hybrid car batteries recharge as you drive so there

is no need to plug in. Most electric cars need to be recharged every 50-100miles. Also,

most electric cars cannot go faster than 50-60 mph, while hybrids can.

Hybrid

cars

bridge

the

gap

between

electric

and

gasoline-powered

cars

by

traveling

further

and

driving

faster

and

hybrid

gas- electric

cars

are

proving

to

be

a

feasible alternative at a time of high gas prices. So, in my opinion, hybrid cars will

have a bright future.

How Does Hybrid Electric Vehicle Work

？

You

probably

own

a

gasoline

or

diesel-engine

car.

You

may

have

heard

of

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electric

vehicles

too.

A

hybrid

vehicle

or

hybrid

electric

vehicle

(HEV)

is

a

combination

of

both.

Hybrid

vehicles

utilize

two

or

more

sources

of

energy

for

propulsion. In the case of HEVs, a combustion engine and an electric motor are used.

How

it

works

depends

on

the

type

of

drive

train

it

has.

A

hybrid

vehicle

can

either have a parallel or series or parallel-series drive train.

Parallel Hybrid

The

parallel

hybrid

car

has

a

gas

tank,

a

combustion

engine,

transmission,

electric motor, and batteries.

A parallel hybrid is designed to run directly from either the combustion engine

or

the

electric

motor.

It

can

run

using

both

the

engine

and

the

motor.

As

a

conventional vehicle, the parallel hybrid draws its power from the combustion engine

which will then drive the transmission that turns the wheels. If it is using the electric

motor, the car draws its power from the batteries. The energy from the batteries will

then power the electric motor that drives the transmission and turns the wheel.

Both

the

combustion

engine

and

the

electric

motor

are

used

at

the

same

time

during

quick

acceleration,

on

steep

ascend,

or

when

either

the

engine

or

the

motor

needs additional boost.

Since the engine is directly connected to the wheels in a parallel drive train, it

eliminates the inefficiency of converting mechanical energy into electrical energy and

back. This makes a very effective vehicle to drive on the highway.

Series Hybrid

The

series

hybrid

car

also

has

a

gas

tank,

a

combustion

engine,

transmission,

electric motor, and batteries with the addition of the generator. The generator can be

the electric motor or it can be another separate component.

The

series

configuration

is

the

simplest

among

the

3.

The

engine

is

not

connected to the transmission rather it is connected to the electric motor. This means

that the transmission can be driven only by the electric motor which draws its energy

from the battery pack, the engine or the generator.

A hybrid car with a series drive train is more suited for city driving conditions

since the engine will not be subjected to the varying speed demands (stop, go, and idle)

that contributes to fuel consumption.

Series-Parallel Hybrid

The series-parallel

configuration solves the individual problems of the parallel

and

series

hybrid.

By

combining

the

2

designs,

the

transmission

can

be

directly

connected

to

the

engine

or

can

be

separated

for

optimum

fuel

consumption.

The

Toyota Prius and the Ford Escape Hybrid use this technology.

Honda

’

s hybrid

For

those

of

you

who

have

toyed

with

the

idea

of

buying

a

hybrid

but

were

discouraged by the price, you are not alone. In fact, despite the growing concern for

the environment, not to mention the skyrocketing price of gas, hybrid cars still only

represent a small percentage of global car sales, and a major reason for this is the cost.

Hybrids

are

considered

the

wave

of

the

future

because

they

not

only

reduce

emissions, addressing the issue of climate change, but they get great gas mileage, an

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important consideration with the current price of oil. It should be noted that hybrids

can also improve the power of the engine, which compromises any advantages in fuel

efficiency and emissions. Whatever the application, however, the technology makes

the cars more expensive.

Because of this, they are the vehicle of choice for only a small niche of people

who

can

afford

them,

and

they

currently

enjoy

a

special

status

amongst

the

image

conscious celebrity-set. For most average consumers, however, they are not an option.

That may soon change.

Honda Motor Corporation, one of the largest car manufacturers in the world and

a

leader

in

fuel

efficient

technology,

has

unveiled

it’s

plan

to

introduce

a

low

-cost

hybrid

by

2009.

If

they

can

pull

it

off,

they

hope

to

make

the

hybrid

a

more

mainstream

car that will be more appealing to

the general

public, with

the ultimate

goal of achieving greater sales and broader appeal than their current incarnation.

This, of course, is making Detroit nervous, and may signal a need for American

car makers to start making greener and more fuel efficient vehicles, something they

could

afford

to

ignore

in

the

past

because

hybrid

cars

weren’t

worth

their

attention

(due

to

such

a

small

market

share)

while

gas- guzzling

SUVs

have

such

high

profit

margins.

Honda, meanwhile, has had to confront a growing need to compete with Toyota,

which has not only grown to be the world’s largest automaker, but makes the car that

has

become

synonymous

with

the

hybrid

movement,

the

Prius.

Honda

is

therefore

faced with the seemingly insurmountable task of challenging Toyota’s dominance in

the market.

Concurrently, Toyota is

racing to lower production costs on the Prius, as well,

which

would

hopefully

result

in

a

lower

cost

to

the

consumer.

All

eyes

are

on

a

potentially favorable car buyers market in 2009.

In the meantime, with even adamant global warming naysayers warming up (no

pun intended) to the possibilities of an ecological disaster on the horizon, maybe it’s

time

that

we

got

over

our

need

to

drive

huge

SUVs

and

start

moderating

our

fuel

consumption.

Then again, as gas prices hovering around $$4.00 and with no ceiling in sight, we

may have little choice in the matter.

Engine Operating Principles

Most

automobile

dngines

are

internal

combustion,

reciprocating

4-stroke

gasoline

engines,

but

other

types

have

been

used,

including

the

diesel,

the

rotary

( Wankel ) , the 2-srtoke, and stratified charge.

Reciprocating

means

up

and

down

or

banck

and

forth,

It

is

the

up

and down

action

of

a

piston

in

the

cylinder

blick,

or

engine

block.

The

blick

is

an

iron

or

aluminum casting that contains engine cylinders and passges called water jackets for

coolant

circulation.

The

top

of

the

block

is

covered

with

the

cylinder

head.

Which

forms the combustion chanber. The bottom of the block is covered with an oil pan or

oil sump.

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Power is produced by the linear motion of a piston in a cylinder. However, this

linear motion must be changed into rotary motion to turn the wheels of cars of trucks.

The piston is attached to the top of a connecting rod by a pin, called a piston pin or

wrist

pin.

The

bottom

of

the

connecting

rod

is

attached

to

the

crankshaft.

The

connecting

rod

transmits

the

up- and-down

motion

of

the

piston

to

the

crankshaft,

which changes it into rotary motion.

The connecting rod is mounted on the crankshaft with large beaings called rod

bearings. Similar bearings, called main bearings, are used to mount the crankshaft in

the block. Shown in Fig. 1-1

The

diameter

of

the

cylinder

is

called

the

engine

bore.

Displacement

and

compression

ratio

are

two

frequently

used

engine

specifications.

Displacement

indicates

engine

size,

and

compression

ratio

compares

the

total

cylinder

volume

to

compression chamber volume.

The

term

stroke

is

used

to

describe

the

movement

of

the

iston

within

the

cylinder, as well as the distance of piston travel. Depending on the type of engine the

operating

cycle

may

require

either

two

or

four

strokes

to

complete.

The

4-stroke

engine is also called Otto cycle engine, in honor of the German engineer, Dr. Nikolaus

Otto, who first applied the principle in 1876. In the 4-stroke engine, four strokes of

the

piston

in

the

cylinder

are

required

to

complete

one

full

operating

cycle.

Each

stroke is named after the action it performs intake, compression, power, and exhaust

in that order, shown in Fig1-2.

1

、

Intake stroke

As the piston moves down, the vaporized mixture of fuel and air enters the cylinder

through open intake valve. To obtain the maximum filling of the cylinder the intake

valve opens about 10°

before t.b.c., giving 20°

overlap. The inlet valve remains open

until some 50°

after b.d.c. to take advantage of incoming mixture.

2

、

Compression stroke

The

piston

turns

up,

the

intake

valve

closes,

the

mixture

is

compressed

within

the

combustion

chamber,

while

the

pressure

rise

to

about

1Mpa,

depending

on

various

factors including the compression ratio, throttle opening and engine speed. Near the

top of the stroke the mixture is ignited by a spark which bridges the gap of the spark

plug.

3

、

Power stroke

The

expanding

gases

of

combustion

produces

a

rise

in

pressure

of

the

gas

to

some

3.5Mpa, and the piston is forced down in the cylinder. The exhaust valve opens near

the bottom of the stroke.

4

、

Exhust stroke

The

piston

moves

back

up

with

the

exhaust

valve

open

some

50°

before

b.d.d.,

allowing the pressure within the cylinder to fall and to reduce ‘back’pressure on the

piston during the exhaust stroke, and the burned gases are pushed out to prepare for

the next intake intake valve usually opens just before the exhaust stroke.

This

4-stroke

cycle

is

continuously

repeared

in

every

as

long

as

the

engineremains

running.

A

2-stroke

engine

also

goes

through

four

actions

to

complete

one

operating

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cycle.

However, the intake and the compression actions are combined in one seroke, and the

power and exhaust actions are combined in the other stroke. The term2-stroke cycle or

2-stroke is preferred to the term 2-cycle, which is really not accurate.

In

automobile

engines,

all

pistons

are

attached

to

a

single

crankshaft.

The

more

cylinders an engine has, the more power strokes produced for cach revolution. This

means that an 8-cylinder engine runs more smoothly bdcause the power atrokes are

closer together in time and in degrees of engine rotation.

The cylinders of multi-cylinder automotive engines arranged in one of three ways.

1

、

Inline engines use a single block of 4-cylinder and any 6-cylinder

engines

are

of

this

design.

The

cylinders

do

not

have

to

be

vertical.

They

can

be

inclined either side.

2

、

V-type

engines

use

two

equal

bands

of

cylinders,

usually

inclined

60degrees

or

90degrees from the cach other. Most V-type engines have 6 or 8 cylinders, although

V-4 and V-12 engines have been built.

3

、

Horizontally

opposed

or

pancake

engines

have

two

equal

banks

of

cylinders

180degreeas

apart.

These

space

saving

engine

designs

are

often

air- cooled,

and

are

found in the Chevrolet Carvair, Porsches, Subaus, and V

olkswagens. Subaus design is

liquid cooled.

Late-model

V

olkswagen

vans

use

a

liquid- cooled

version

of

the

air

cooled

VWhorizontally opposed engine.

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