the hy-wire car

The Hy-Wire Car

Chapter I

INTRODUCTION

Cars are immensely complicated machines, but when you get down

to it, they do an incredibly simple job. Most of the complex stuff in a car is

dedicated to turning wheels, which grip the road to pull the car body and

passengers along. The steering system tilts the wheels side to side to turn the

car, and brake and acceleration systems control the speed of the wheels.

Given that the overall function of a car is so basic (it just needs to

provide rotary motion to wheels), it seems a little strange that almost all cars

have the same collection of complex devices crammed under the hood and the

same general mass of mechanical and hydraulic linkages running throughout.

Why do cars necessarily need a steering column, brake and acceleration pedals,

a combustion engine, a catalytic converter and the rest of it?

According to many leading automotive engineers, they don't; and

more to the point, in the near future, they won't. Most likely, a lot of us will be

driving radically different cars within 20 years. And the difference won't just

be under the hood -- owning and driving cars will change significantly, too.

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The Hy-Wire Car

In this article, we'll look at one interesting vision of the future,

General Motor's remarkable concept car, the Hy-wire. GM may never actually

sell the Hy-wire to the public, but it is certainly a good illustration of various

ways cars might evolve in the near future.

GM's sedan model Hy-wire

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The Hy-Wire Car

Chapter- II

HY-WIRE BASICS

Two basic elements largely dictate car design today: the internal

combustion engine and mechanical and hydraulic linkages. If you've ever

looked under the hood of a car, you know an internal combustion engine

requires a lot of additional equipment to function correctly. No matter what

else they do with a car, designers always have to make room for this

equipment.

The same goes for mechanical and hydraulic linkages. The basic idea

of this system is that the driver maneuvers the various actuators in the car (the

wheels, brakes, etc.) more or less directly, by manipulating driving controls

connected to those actuators by shafts, gears and hydraulics. In a rack-and-

pinion steering system, for example, turning the steering wheel rotates a shaft

connected to a pinion gear, which moves a rack gear connected to the car's

front wheels. In addition to restricting how the car is built, the linkage concept

also dictates how we drive: The steering wheel, pedal and gear-shift system

were all designed around the linkage idea.

The defining characteristic of the Hy-wire (and its conceptual

predecessor, the Autonomy) is that it doesn't have either of these two things.

Instead of an engine, it has a fuel cell stack, which powers an electric motor

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The Hy-Wire Car

connected to the wheels. Instead of mechanical and hydraulic linkages, it has a

drive by wire system -- a computer actually operates the components that move

the wheels, activate the brakes and so on, based on input from an electronic

controller. This is the same control system employed in modern fighter jets as

well as many commercial planes.

The result of these two substitutions is a very different type of car --

and a very different driving experience. There is no steering wheel, there are

no pedals and there is no engine compartment. In fact, every piece of

equipment that actually moves the car along the road is housed in an 11-inch-

thick (28 cm) aluminum chassis -- also known as the skateboard -- at the base

of the car. Everything above the chassis is dedicated solely to driver control

and passenger comfort.

This means the driver and passengers don't have to sit behind a mass

of machinery. Instead, the Hy-wire has a huge front windshield, which gives

everybody a clear view of the road. The floor of the fiberglass-and-steel

passenger compartment can be totally flat, and it's easy to give every seat lots

of leg room. Concentrating the bulk of the vehicle in the bottom section of the

car also improves safety because it makes the car much less likely to tip over.

But the coolest thing about this design is that it lets you remove the

entire passenger compartment and replace it with a different one. If you want

to switch from a van to a sports car, you don't need an entirely new car; you

just need a new body (which is a lot cheaper).

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The Hy-Wire Car

The Hy-wire has wheels, seats and windows like a conventional car, but the similarity pretty much ends there. There is no engine under the hood and no

steering wheel or pedals inside.

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The Hy-Wire Car

Chapter III

POWER

The "Hy" in Hy-wire stands for hydrogen, the standard fuel for a fuel

cell system. Like batteries, fuel cells have a negatively charged terminal and a

positively charged terminal that propel electrical charge through a circuit

connected to each end. They are also similar to batteries in that they generate

electricity from a chemical reaction. But unlike a battery, you can continually

recharge a fuel cell by adding chemical fuel -- in this case, hydrogen from an

onboard storage tank and oxygen from the atmosphere.

The basic idea is to use a catalyst to split a hydrogen molecule (H2)

into two H protons (H+, positively charged single hydrogen atoms) and two

electrons (e-). Oxygen on the cathode (positively charged) side of the fuel cell

draws H+ ions from the anode side through a proton exchange membrane, but

blocks the flow of electrons. The electrons (which have a negative charge) are

attracted to the protons (which have a positive charge) on the other side of the

membrane, but they have to move through the electrical circuit to get there.

The moving electrons make up the electrical current that powers the various

loads in the circuit, such as motors and the computer system. On the cathode

side of the cell, the hydrogen, oxygen and free electrons combine to form water

(H2O), the system's only emission product.

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The Hy-Wire Car

In a hydrogen fuel cell, a catalyst breaks hydrogen molecules in the anode into protons and electrons. The protons move through the exchange membrane, toward the oxygen on the cathode side, and the electrons make their way through a wire between the anode and cathode. On the cathode side, the hydrogen and oxygen combine to form water. Many cells are connected in series to move substantial charge through a circuit.

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The Hy-Wire Car

In a hydrogen fuel cell, a catalyst breaks hydrogen molecules in the

anode into protons and electrons. The protons move through the exchange

membrane, toward the oxygen on the cathode side, and the electrons make

their way through a wire between the anode and cathode. On the cathode side,

the hydrogen and oxygen combine to form water. Many cells are connected in

series to move substantial charge through a circuit.

One fuel cell only puts out a little bit of power, so you need to combine

many cells into a stack to get much use out of the process. The fuel-cell stack

in the Hy-wire is made up of 200 individual cells connected in series, which

collectively provide 94 kilowatts of continuous power and 129 kilowatts at

peak power. The compact cell stack (it's about the size of a PC tower) is kept

cool by a conventional radiator system that's powered by the fuel cells

themselves.

The hydrogen tanks and fuel-cell stack in the Hy-wire

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The Hy-Wire Car

This system delivers DC voltage ranging from 125 to 200 volts,

depending on the load in the circuit. The motor controller boosts this up to 250

to 380 volts and converts it to AC current to drive the three-phase electric

motor that rotates the wheels (this is similar to the system used in conventional

electric cars).

The electric motor's job is to apply torque to the front wheel axle to

spin the two front wheels. The control unit varies the speed of the car by

increasing or decreasing the power applied to the motor. When the controller

applies maximum power from the fuel-cell stack, the motor's rotor spins at

12,000 revolutions per minute, delivering a torque of 159 pound-feet. A single-

stage planetary gear, with a ratio of 8.67:1, steps up the torque to apply a

maximum of 1,375 pound-feet to each wheel. That's enough torque to move the

4,200-pound (1,905-kg) car 100 miles per hour (161 kph) on a level road.

Smaller electric motors maneuver the wheels to steer the car, and electrically

controlled brake calipers bring the car to a stop.

The gaseous hydrogen fuel needed to power this system is stored in

three cylindrical tanks, weighing about 165 pounds (75 kilograms) total. The

tanks are made of a special carbon composite material with the high structural

strength needed to contain high-pressure hydrogen gas. The tanks in the current

model hold about 4.5 pounds (2 kg) of hydrogen at about 5,000 pounds per

square inch (350 bars). In future models, the Hy-wire engineers hope to

increase the pressure threshold to 10,000 pounds per square inch (700 bars),

which would boost the car's fuel capacity to extend the driving range.

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The Hy-Wire Car

Ultimately, GM hopes to get the fuel-cell stack, motors and

hydrogen-storage tanks small enough that they can reduce the chassis thickness

from 11 inches to 6 inches (15 cm). This more compact "skateboard" would

allow for even more flexibility in the body design.

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The Hy-Wire Car

Chapter IV

CONTROL

The Hy-wire's "brain" is a central computer housed in the middle of

the chassis. It sends electronic signals to the motor control unit to vary the

speed, the steering mechanism to maneuver the car, and the braking system to

slow the car down.

At the chassis level, the computer controls all aspects of driving and

power use. But it takes its orders from a higher power -- namely, the driver in

the car body. The computer connects to the body's electronics through a single

universal docking port. This central port works the same basic way as a USB

port on a personal computer: It transmits a constant stream of electronic

command signals from the car controller to the central computer, as well as

feedback signals from the computer to the controller. Additionally, it provides

the electric power needed to operate all of the body's onboard electronics. Ten

physical linkages lock the body to the chassis structure.

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The Hy-Wire Car

GM's diagram of the Autonomy design

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The Hy-Wire Car

The driver's control unit, dubbed the X-drive, is a lot closer to a video

game controller than a conventional steering wheel and pedal arrangement.

The controller has two ergonomic grips, positioned to the left and right of a

small LCD monitor. To steer the car, you glide the grips up and down lightly --

you don't have to keep rotating a wheel to turn, you just have to hold the grip in

the turning position. To accelerate, you turn either grip, in the same way you

would turn the throttle on a motorcycle; and to brake, you squeeze either grip.

Electronic motion sensors, similar to the ones in high-end computer

joysticks, translate this motion into a digital signal the central computer can

recognize. Buttons on the controller let you switch easily from neutral to drive

to reverse, and a starter button turns the car on. Since absolutely everything is

hand-controlled, you can do whatever you want with your feet (imagine

sticking them in a massager during the drive to and from work every day).

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The Hy-Wire Car

The Hy-wire's X-drive

The X-drive can slide to either side of the vehicle.

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The Hy-Wire Car

The 5.8-inch (14.7-cm) color monitor in the center of the controller

displays all the stuff you'd normally find on the dashboard (speed, mileage,

fuel level). It also gives you rear-view images from video cameras on the sides

and back of the car, in place of conventional mirrors. A second monitor, on a

console beside the driver, shows you stereo, climate control and navigation

information.

Since it doesn't directly drive any part of the car, the X-drive could

really go anywhere in the passenger compartment. In the current Hy-wire

sedan model, the X-drive swings around to either of the front two seats, so you

can switch drivers without even getting up. It's also easy to adjust the X-drive

up or down to improve driver comfort, or to move it out of the way completely

when you're not driving.

One of the coolest things about the drive-by-wire system is that you

can fine-tune vehicle handling without changing anything in the car's

mechanical components -- all it takes to adjust the steering, accelerator or

brake sensitivity is some new computer software. In future drive-by-wire

vehicles, you will most likely be able to configure the controls exactly to your

liking by pressing a few buttons, just like you might adjust the seat position in

a car today. It would also be possible in this sort of system to store distinct

control preferences for each driver in the family.

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The Hy-Wire Car

.

GM concept of the Autonomy with and without a body attached

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The Hy-Wire Car

The big concern with drive-by-wire vehicles is safety. Since there is

no physical connection between the driver and the car's mechanical elements,

an electrical failure would mean total loss of control. In order to make this sort

of system viable in the real world, drive-by-wire cars will need back-up power

supplies and redundant electronic linkages. With adequate safety measures like

this, there's no reason why drive-by-wire cars would be any more dangerous

than conventional cars. In fact, a lot of designers think they'll be much safer,

because the central computer will be able to monitor driver input. Another

problem is adding adequate crash protection to the car.

The other major hurdle for this type of car is figuring out energy-

efficient methods for producing, transporting and storing hydrogen for the

onboard fuel-cell stacks. With the current state of technology, actually

producing the hydrogen fuel can generate about as much pollution as using

gasoline engines, and storage and distribution systems still have a long way to

go (see How the Hydrogen Economy Works for more information).

So will we ever get the chance to buy a Hy-wire? General Motors

says it fully intends to release a production version of the car in 2010,

assuming it can resolve the major fuel and safety issues. But even if the Hy-

wire team doesn't meet this goal, GM and other automakers are definitely

planning to move beyond the conventional car sometime soon, toward a

computerized, environmentally friendly alternative. In all likelihood, life on the

highway will see some major changes within the next few decades.

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The Hy-Wire Car

Chapter -V

HY-WIRE CAR SPECIFICATION

Top speed: 100 miles per hour (161 kph)

Weight: 4,185 pounds (1,898 kg)

Chassis length: 14 feet, 3 inches (4.3 meters)

Chassis width: 5 feet, 5.7 inches (1.67 meters)

Chassis thickness: 11 inches (28 cm)

Wheels: eight-spoke, light alloy wheels.

Tires: 20-inch (51-cm) in front and 22-inch (56-cm) in back

Fuel-cell power: 94 kilowatts continuous, 129 kilowatts peak

Fuel-cell-stack voltage: 125 to 200 volts

Motor: 250- to 380-volt three-phase asynchronous electric motor

Crash protection: front and rear "crush zones" (or "crash boxes") to

absorb impact energy

Related GM patents in progress: 30

GM team members involved in design: 500+

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The Hy-Wire Car

CONCLUSION

By using Hy-Wire technology certain multi national companies like

General Motors is fully intended to release a production version of the car in

2010, assuming it can resolve the major fuel and safety issues. The life on the

high way will see some major changes within the next few decades.

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The Hy-Wire Car

REFERENCES

www.howstuffworks.com

www.generalmoters.com

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The Hy-Wire Car

ACKNOWLEDGEMENT

First of all I thank the almighty for providing me with the strength and

courage to present the seminar.

I avail this opportunity to express my sincere gratitude towards

Dr. T.N. Sathyanesan, head of mechanical engineering department, for

permitting me to conduct the seminar. I also at the outset thank and express my

profound gratitude to my seminar guide Mr. Sasikumar and staff incharge

Asst. Prof. Mrs. Jumailath Beevi. D., for their inspiring assistance,

encouragement and useful guidance.

I am also indebted to all the teaching and non- teaching staff of the

department of mechanical engineering for their cooperation and suggestions,

which is the spirit behind this report. Last but not the least, I wish to express

my sincere thanks to all my friends for their goodwill and constructive ideas.

RIJIL K.P.

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The Hy-Wire Car

ABSTRACT

Hy-Wire Car is without mechanical and hydraulic linkage end engine.

Instead of these it contain a fuel cell stack and a drive by wire system. It is

fully automated car it is a future car. In future it will have a wide application.

The problem with fuel consumption and pollution can be minimize to certain

level.

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The Hy-Wire Car

CONTENTS

1. INTRODUCTION 1

2. HY-WIRE BASICS 3

3. POWER 6

4. CONTROL 11

5. HY-WIRE CAR SPECIFICATION 18

6. CONCLUSION 19

7. REFERENCES 20

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