DIFFERENTIAL BASED HEADLIGHT SYSTEM.doc

DEPARTMENT OF MECHANICAL ENGINEERING

DIFFERENTIAL BASED HEADLIGHT

SYSTEM

SUBMITTED BY

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ABSTRACT

Our project is to make new and modern “Directional Headlights” in efficient

manner by increasing the light angle. Directional headlights are those headlights

that provide improved lighting especially for cornering. There are automobiles

that have their headlights directly connected to the steering mechanism so that

its lights will follow the movement of the front wheels.

Our project comprises Cam and Follower mechanism, Gear mechanism and

spring mechanism. Cam and Follower mechanism is used to turn the head lights

to right or left direction, Gear mechanism is used to transmit motion and to

reduce the no of rotations from steering rod to cam shaft. Spring mechanism is

used to bring back the follower and head light bracket to its initial position.

According to our project, when the steering steers to the right, the light bracket

at right alone steers to right using cam & follower mechanism and reduction

gears & vice versa. At the same time the left bracket remains stand still due to

the dwell period of the cam. During the return stroke of cam, the spring

mechanism is used to bring the bracket and follower to its initial position. The

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reduction gears are used to turn the brackets to the required angle respective to

the steering rotation.

Our project will be useful for vehicles, which are been used in hill

areas

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1. INTRODUCTION

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The present invention relates to headlights of an automobile, more particularly to a

direction turning device for headlights of an automobile which enables to turn direction

synchronously with the rotation of the steering and hence increasing the safety for driving

at night or in the darkness.

In the known technology of the prior art, a headlight of an automobile has a

fixed line of emission which is aligned with the front direction of the automobile.

Although the effects of "high beam" or "low beam" can be achieved by adjusting the

angle of elevation of the headlight, the direction of emission is not adjustable as to the

left or right. When the road curves or turns, the corner on time when the car turns,

thereby creating a dead angle of illumination and such lack of visibility poses danger in

driving at night or in darkness.

Therefore, it is highly desirable to invent a device to solve this problem and

such device is of high utility.

An object of the present invention is to provide a direction turning device for a

headlight of an automobile which renders to emission direction of a headlight of an

automobile in synchronization with steering and thus increases the illuminated area upon

changes of direction of the automobile when the automobile makes turns.

In ancient Directional headlights, When the steering steers to right or left

direction, then both the right and left headlights will steer to the perspective directions. It

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results in altering the optical axis of the head light to the vehicle speed and the front road-

shape.

But according to our project, when the steering steers to right then the right

side of the headlight bracket steers to right side and the left side headlight bracket

remains stationery by cam mechanism and it is similar for the other side also. Because of

this, the optical axis of the headlight is widened and it is useful for the drivers for safety

ride.

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2. LITERATURE REVIEW

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Our mechanism is not used elsewhere in any of the vehicles. We

performed a survey on this project with the lorry drivers, who travel to hill

stations often. Based on their queries, we had indulged in this project.

The present invention relates to a vehicle front lamp light distribution

control system and more particularly to a vehicle front lamp light

distribution control system capable of raising visibility at the time of

cornering by controlling light distribution means of the front lamp.

According to Japanese Patent Publication No. H5-23216, Japanese Patent

Application Laid-Open No. H8-183385, Japanese Patent Application Laid-

Open No. H11-78675 and Japanese Patent Application Laid-Open No. H8-

192674 a vehicle head lamp including a fog lamp is provided with a

movable reflector and by turning the movable reflector in the steering

direction by an amount corresponding to a steering angle of the steering

wheel, the light distribution pattern of the front lamp is changed in the

direction of vehicle's turn so as to raise visibility at the time of cornering.

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However, according to the aforementioned earlier art, the light distribution

pattern of the front lamp is changed in the steering direction of the steering

wheel by an amount corresponding to the steering angle when the vehicle

turns on an intersection or the like, cornering destination cannot be beamed

brightly enough before operating the steering wheel. Therefore, an art

capable of beaming the cornering destination prior to operation of the

steering wheel has been demanded.

Czech Tatra and 1920s Cadillacs were early implementer of such a

technique, producing in the 1930s a vehicle with a central directional

headlamp. The American 1948 Tucker Sedan was likewise equipped with a

third central headlamp connected mechanically to the steering system. The

1967 French Citroën DS and 1970 Citroën SM were equipped with an

elaborate dynamic headlamp positioning system that adjusted the

headlamps' horizontal and vertical positioning in response to inputs from

the vehicle's steering and suspension systems, though US regulations

required this system to be deleted from those models when sold in the

USA.

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3. CONSTRUCTION

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The main components used in this project are:

3.1 Spur Gears:

Spur gears are the simplest, and probably most common, type of gear. Their

general form is a cylinder or disk.

The teeth project radially, and with these "straight-cut gears", the leading

edges of the teeth are aligned parallel to the axis of rotation. These gears can

only mesh correctly if they are fitted to parallel axis.

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3.2 Sprockets:

A sprocket is a profiled wheel with metal teeth that meshes with a chain,

track or other perforated or indented material. Sprockets are used to transmit

rotary motion between two shafts where gears are unsuitable or to impart

linear motion to a track, tape etc.

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3.3 Cam & follower:

Cams are basically shaped surfaces that are typically not round

follower(possibly a small wheel) is displaced as it moves over the surface.

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3.4 Steering system:

The most conventional steering arrangement is to turn the front wheels using

a handle operated steering wheel which is positioned in front of the driver,

via the steering column, which may contain universal joints to allow it to

deviate somewhat from a straight line. Other arrangements are sometimes

found on different types of vehicles, for example, a tiller or rear wheel

steering. Tracked vehicles such as tanks usually employ differential steering

that is, the tracks are made to move at different speeds or even in opposite

directions to bring about a change of course.

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3.5 Light bracket:

Headlamps must be kept in proper alignment (or "aim"). Regulations for aim

vary from country to country and

From beam specification to beam specification. This gives all vehicles

roughly equal seeing distance and all drivers roughly equal glare.

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3.6 Frames

Framing, in construction known as light frame construction, is a building

technique based around structural members, usually called studs, which

provide a stable frame to which interior and exterior wall coverings are

attached, and covered by a roof comprising horizontal joists and sloping

rafters or manufactured roof trusses covered by various sheathing materials.

Light frame material dimensions range from 38 mm by 89 mm (1.5 by 3.5

inches — i.e. a two-by-four) to 5 cm by 30 cm (two-by-twelve inches) at the

cross-section, and lengths ranging from 2.5 m (8 feet) for walls to 7 m (20

feet) or more for joists and rafters.

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http://en.wikipedia.org/wiki/Image:ToyotaTundraChassis.jpg

3.7 Chain drive:

Commonly, mechanical energy from a motor or other source applied to a

sprocket wheel is conveyed by means of an endless chain to another

sprocket wheel for driving a mechanism. Examples of such an arrangement

are found in bicycles, motorcycles, and conveyor belts.

The chain in this application is so designed that each consecutive link fits

over a sprocket, the distance between links being called the pitch. The

relative speed of the wheels varies according to their relative circumferences

and, thus, the number of sprockets on each.

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4. WORKING METHODOLOGY

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Our project is to the turn the right light bracket to the right, when the vehicle

turns to right leaving the left bracket to remain in standstill position, and

vice versa.

When the steering steers to the right, a sprocket attached to the steering rod

rotates which in turn connected to the other sprocket through a chain. The

sizes of the sprockets were designed in such a way that, if the smaller

sprocket rotates four full complete rotations the larger sprocket will rotate

once. Also the small gear, which is attached to the same shaft as of the

larger sprocket, also rotates along with the sprocket.

A larger gear of the former is chosen, which is twice its diameter, is meshed

to transmit the motion. After this, the rotation of cam is achieved by fixing

the cam in the same shaft of the larger gear. The spherical edged follower is

attached to the cam is used to convert the rotary motion of cam into

reciprocating motion. So the right light bracket moves according to the

movement of the follower. At the same time, the cam at the other end

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remains in the dwell period, which results in the stand still position of the

light bracket.

The light bracket will returns back to its original position, using the spring

mechanism attached to it.

When the vehicle turns to left, the left bracket alone turns to the left leaving

the right light bracket in standstill position.

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INITIAL HEADLIGHT POSITION

FINAL HEADLIGHT POSITION

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5. DESIGN CALCULATIONS

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5.1. Design calculation for chain drive

Speed of rotation, N1 = 1000 rpm


Centre distance, a = 800 mm

Gear ratio, i = N1/N2 = 4

istd = 4

Teethes, z1 = 20

Teethes, z2 = i * z1 = 80 teeth

Chain pitch, a = (30 – 50) p

a = 30p => p= 26.67 mm =pmax

a = 50p => p= 16 mm =pmin

Standard pitch, p std =25.4 mm

So the chain selected is 16A1-R80-> simplex

Length of chain,

lp = 2ap + (z1+z2)/2+((z2-z1)/2)2/ap

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ap = ao/p = 800/25.4 = 31.49

lp = (2*31.49)+50+(60/2*3.14)2/31.49

= 115.87

= 116 links

Actual length = no. of links * pitch

= 2946.6 mm

Bearing area = 1.79 mm2

Centre distance, a = ((e+√(e2 -8m))/4)p

e = lp – (z1+z2)/2 = 66

m = ((z2-z1)/(2*3.14))2 = 91.18

a = 66+√(((662 – (8*91.18))/4)p = 801.5 mm

5.2. Design calculation for chain drive



Centre distance, a = 1200 mm


istd = 4

Teethes, z1 = 20

Teethes, z2 = i * z1 = 80 teethes

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Chain pitch, a = (30 – 50)p

a = 30p => p= 40 mm =pmax

a = 50p => p= 24 mm =pmin

Standard pitch, p std =25.4 mm

So the chain selected is 16A1-R80-> simplex

Length of chain,

lp = 2ap + (z1+z2)/2+((z2-z1)/2)2/ap

ap = ao/p = 1200/25.4 = 47.24

lp = (2*47.24)+50+(60/2*3.14)2/47.24

= 144.49

= 146 links

Actual length = no. of links * pitch

= 3708.4 mm

Bearing area = 1.79 mm2 Centre distance, a = ((e+√(e2 -8m))/4)p

e = lp – (z1+z2)/2 = 96

m = ((z2-z1)/(2*3.14))2 = 91.18

a = 96+√(((962 – (8*91.18))/4)p

= 1194.5 mm

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5.3. Rotation reduction ratios

Steering rotation = 7200

Angle of cam to be tilted = 900

So value of angle to be reduced is in ratio 8:1

The reduction between the sprockets is made as 4:1

So the diameter & teeth of the larger sprocket should be four times that of

the smaller

Diameter, d1 = 40 mm

Teethes, z1 = 20


Teethes, z1 = 80

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5.4. Design calculation for spur gears




Assuming the same material for pinion and gear

16Ni 1 Cr80

Life of gear = 20,000 hours

Number of cycles = 20,000*60*N1

= 20,000*60*1000

= 1.2*109 cycles

Young’s modulus, E = 2.15*106 kgf/cm2

= 2.15*105 N/mm2

Design contact stress, [σc] = CR * HRC*Kcl

CR = 310, HRC = 60, Kcl= 1 {from psg tech data book pg.No.8.17}

[σc] = 18.6 * 102 N/mm2

Design bending stress, [σb] = ((1.4*Kbl*σ-1)/(n*Kσ))

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N = 2, Kσ = 1.2, Kbl = 1

σ-1 = 0.25σu + 1200

σu = 1000 N/mm2

σ-1 = 47000 N/cm2

[σb] = 274.16 N/mm2

k.kd = 1.3

ko = 1.5(medium shock)

Teethes, z1 = 20

Teethes, z2= i*z1 = 40

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5.5. Design calculation for sprockets

Here the rotation reduction ratio is 4:1

So the diameter & teeth of larger sprocket should be four times that of the

smaller.

Diameter, d1 = 40 mm [readily available in market]

Teethes, z1 = 20


Teethes, z2 = 80

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5.6. Design calculation for cam & follower

OA = initial position of light bracket (7inches)

AB = final position of light bracket

OB = distance moved by the bracket

Stroke length = 102.6 mm

Cam diameter = 150 mm

Follower length = 102.6 mm

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5.7. Sprocket & Gear details, we selected due to availability in market:

S.No. Component Material No. of teethes Diameter

1. Small Sprocket Mild steel 20 40

2. Large Sprocket Mild steel 80 160

3. Small Gear Mild steel 20 40

4. Large Gear Mild steel 40 80

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6. RESULT & FUTURE APPLICATIONS

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6.1 ADVANTAGES

Useful for heavy vehicles in hill areas, where hair-pin bends are more.

Safe riding

Accident free roads

Simple in structure

Mind free driving

6.2 LIMITATIONS

Not mandatory for straight roads.

6.3 APPLICATIONS

Can be used in all heavy vehicles.

Can be used in tempo and vans.

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7. BIBLIOGRAPHY

1. Book on “Design of Machine Elements” by K.V.NATARAJAN

2. Book on “Design of Transmission Systems” by V.BANDARI

3. PSG Design Data Book.

4. www.wikipedia.com

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DIFFERENTIAL BASED HEADLIGHT SYSTEM.doc

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