A

REPORT ON UTILITY OF CAM FOLLOWER

IN SINGLE CYLINDER FOUR STROKE SPARK

IGNITION ENGINE

HARDWARE PROJECT REPORT 2014/15

SUBMITTED BY- GUIDE&CO-GUIDE

PIYUSH KUMAR TIWARI 1101201022 DR. HARSHDEEP SHARMA

GAURAV BHATI 1101201049 DR. KRISHNA VIJAY OJHA

NITESH KUMAR JHA 1101201038

ABHISHEK KR. CHAUDHARY 1101201110

RITESH KUMAR SINGH 1101201060

VISHAL KUMAR 1101201042

ACKNOWLEDGEMENT

We are deeply grateful to DR.HARSHDEEP

SHARMA AND DR.KRISHNA VIJAY OJHA Who

gave us a chance to model work on the topic of

cam/follower utility in single cylinder four stroke

S.I. engine. They provide us valuable suggestion

on this model for which we are highly obliged.

This model helps to the fresher students of

mechanical engineering to understand the basic

working and concept of cam/follower in engines.

We have try our best to ensure the model free of

error but small mistakes may be possible by

human mistake.

GROUP MEMBERS-

PIYUSH KUMAR TIWARI

GAURAV BHATI

NITESH KUMAR JHA

ABHISHEK KUMAR CHAUDHARY

RITESH KUMAR SINGH

VISHAL KUMAR

LIST OF CONTENT

1. Certificate

2. Acknowledgement

3. Introduction

4. Types of cam

5. Types of follower and geometry

6. Working and dimension analysis

7. Cost analysis and purpose

8. References.

INTRODUCTION

The cam follower is interesting mechanical device

which is use to convert the motions of any link

into desired way.

This is broadly use in engines for governing the

valve timing in during the starting conditions. The

fuel control and exhaust gases blow out is also

done by this interesting device. Now days due to

complex mechanism and fuel economy this is

change by variable valve timing. The cam/follower

is supported by a rigid frame which controls the

motion and keep safe the device from irregular

motions and damage. The cam/follower is might

be gravity type or spring loaded. Depending upon

the accuracy the cam/follower are selected and

according to speed variation.

TYPES OF CAM

CAMS ARE CLASSIFIED ACCORDING TO-

1. SHPE.

2. FOLLOWER MOVEMENT.

3. MANNER OF CONSTRAINT OF THE FOLLOWER.

ACCORDING TO SHAPE-

(a)WEDGE CAM- A wedge cam has a wedge which,

in general has a transnational motion. The

follower can either translate or oscillate. A spring

is usually, used to maintain the contact between

the cam and the follower.

(b) RADIAL/DISC CAM- A came in which the

follower moves radially from center of rotation of

the cam is known as a radial or disc cam.

DISC CAM

(c) SPIRAL CAM- A spiral cam is a face cam in

which a groove is cut from of a spiral .The spiral

groove consists of teeth which mesh with a pin

gear follower.

(d) CYLINDRICAL CAM- In a cylindrical cam, a

cylinder which has a circumferential contour cut

in the surface, rotates about its axis. Cylindrical

cam are also known as barrel or drum cam.

CYLINDICAL CAM

(e)CONJUGATE CAM- A conjugate cam is a double-

disc cam, the two discs being keyed together and

are in constant touch with the two rollers of

follower.

Thus the follower has the positive constraint. Such

a type of cam is preferred when the requirements

are low wear and low noise, high speed, accuracy.

These cam can also be uses in high dynamic load.

CONJUGATE CAM

(f)GLOBOIDAL CAM- A globoidal cam can have

two types of surfaces convex and concave. A

circumferential contour is cut on the surface on

the rotation of the cam to the follower which has

an oscillatory motion.

(g) SPHERICAL CAM- In a spherical cam, the

follower oscillates about an axis perpendicular to

the axis of rotation of the cam.

SPHERICAL CAM

ACCORDING TO THE FOLLOWER MOVEMENT-

(a) RISE-RETURN-RISE.

(b) DWELL-RISE-RETURN-DWELL.

(c) DWELL-RISE-DWELL-RETURN-DWELL.

DWELL –NO MOTION CONSTANT.

RISE- UP LIFT.

RETURN- COME DOWN.

COMINED SCHEMATIC DIGRAMS

ACCORDING TO CONSTRAINT OF THE FOLLOWER

(a) PRE-LOADED SPRING CAM- A pre-loaded

compression spring is used for the purpose

of keeping the contact between the cam

and the follower.

(b) POSITIVE-DRIVE CAM- In this type, constant

touch is maintained.

(c) GRAVITY CAM- If the rise/return is occurred

due to self-weight of follower.

TYPES OF FOLLOWERS

FOLLOWERS ARE CLASSIFIED ACCORDING TO –

1. SHAPE.

2. MOVEMENT.

3. LOCATION OF THE LINE OF THE MOVEMENT.

ACCORDING TO SHAPE-

(a) KNIFE-EDGE FOLLOWER-It is quite simple in

construction, the end edges are too sharp

and causes wear on the cam.

KNIFE EDGE FOLLOWER

(b) ROLLER-FOLLOWER- It is a widely used cam

follower and has a cylindrical roller free to

rotate about a pin joint.

(c) MUSHROOM FOLLOWER- A mushroom

followers has the advantages that it does

not have a problem of jamming. But the

surface stress are quite high.

ACCORDING TO THE MOVEMENT-

(a) RADIAL FOLLOWER- In this, type as the cam

rotates, the follower reciprocates or

translates in the guides.

(b) OSCILLATING FOLLOWER- The follower is

pivoted at a suitable point on the frame and

oscillates as the cam makes the rotary

motion.

ACCORDING TO LOCATION OF LINE OF

MOVEMENT-

(a)RADIAL FOLLOWER-The follower is known as

a radial follower if the line of movement of the

follower passes through the center of rotation

of the cam.

(b)OFFSET FOLLOWER-If the line of movement

of the roller follower is offset from the center of

the rotation of the cam, the follower is known

as the offset follower.

GEOMETRY

BASE CIRCLE- It is the smallest circle tangent to

the cam profile (contour) drawn from the center

of rotation of a radial cam.

TRACE POINT- It is a reference point on the

follower to trace the cam profile such as the knife-

edge of a knife-edged follower and center of the

roller of the roller follower.

PITCH CIRCLE- It is curve drawn by the trace point

assuming that the cam is fixed, and the trace

point rotates around the cam.

PRESSURE ANGLE- The pressure representing the

steepness of the cam profile, is the angle between

the normal to the pitch curve at a point and

direction of the follower motion. It varies in

magnitude in all instant of the follower motion.

PITCH POINT- It is the point on the pitch curve at

which the pressure angle is maximum.

PITCH CIRCLE- It is the circle passing through the

pitch point and concentric with the base circle.

PRIME CIRCLE- The smallest circle drawn tangent

to the pitch curve is known as the prime circle.

UTILITY IN SI ENGINE (WORKING)

The cam/follower is used in engines for governing

the valve timing and open and close it for

particular time and degree of crank rotation.

FOUR STROKE SI ENGINE-

Consist of four stroke-

1. SUCTION. INLET VALVE OPEN.

2. COMPRESSION. BOTH VALVE CLOSE.

3. EXPANSION. BOTH VALVE CLOSE.

4. EXHAUST. EXHAUST VALVE OPEN.

Schematic diagram of four strokes.

STANDARD MODEL

FABRICATED MODEL

DIMENSIONS ANALYSIS

1. THICKNESS OF THE WOOD 0.5 INCH.

2. CRANK LENGTH 4 INCH.

3. CONNECTING ROD LENGTH 8 INCH.

4. FRAME LENGTH 12-12 INCH.

5. CYLINDER HEIGHT 7 INCH.

6. BORED DIAMETER 2.5 INCH.

7. DISC CAM 1 INCH

BORE.

8. CRANK SHAFT DIAMETER 1 INCH.

9. PUSH ROD LENGTH 17 INCH.

10. CLEARANCE LENGTH 1.5 INCH.

The valve opening and closing is depend upon the

orientation of the cam. The two cam are situated

at 180 to each other. The valve timing is very

sophisticated phenomena which requires high

degree of accuracy and perfect timing balance.

The cam angle change as per crank rotation and it

is calibrated very carefully.

In multi cylinder engine the timing of valves gets

too tough job and done carefully.

As we can see from the above diagram that the

valve is supported by rocker arm and the motion

is govern by cam motion.

THE Cam-follower movement is done by the cam-

shaft and timing chain, but in some case the cam

shaft is directly coupled with the main crank-shaft

of engine.

In present model the cam shaft and crank shaft is

common. This increases mechanical efficiency and

reduces extra mechanical linkage.

But for maintenance purpose you have to open

the whole engine.

FROM ABOVE DIAGRAM IT IS CLEARED THAT THE

CAM SHAFT IS COUPLED BY THE TIMING CHAIN TO

THE MAIN CRANK SHAFT. AND THE CAMS ARE

MOUNTED ON THIS CAM SHAFT.

COST ANALYSIS AND PURPOSE

The overall cost of this model is 1500 rupees.

1. Wood INR 700.

2. CAM INR 150

3. MACHINING CHARGE INR 400.

4. FEVICOL&NAIL ETC INR 250.

PUPPOSE OF MODEL-

This model is made for understanding the

concept of cam-follower in internal combustion

engines. It helps the fresher students of

mechanical engineering to learn the concepts in

practical manner. It also an attempt to use the

bookish knowledge into practical work.

REFERENCES

1. I.C.ENGINE BY V.GANESHAN.

2. THEORY OF MACHINE BY

S.S.RATTAN.

3. GOOGLE IMAGES ON

CAM/FOLLOER.

4. LINK ADRESS-

http://en.wikipedia.org/wi

ki/Cam_follower.