vehicle power train auto 1032 report

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Engine design challenge AUTO-1032 2010

RMIT UNIVERSITY

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ANAND KIRAN .N (S3223883)

VEHICLE POWER TRAIN AUTO 1032-

ENGINE DESIGN CHALLENGE

DR .LUCIEN KOOPMANS

THOMAS ROGERS

N.ANAND KIRAN

S3223883


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CONTENTS

yABSTRACTyINTRODUCTIONyDESIGN JUSTIFICATIONSyENGINE LAYOUTyCONCLUSIONSyREFERENCES


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ABSTRACT

The automotive industry is considered to be the booming industry from nineteenth century.

Radical changes in this sector can be noticed in everyday life. Most importantly designing an

engine plays a prominent role in development of a vehicle. From technological point of view

even though many engine manufacture companies are producing many reliable engines wecan still notice few limitations in terms of fuel consumption and performance. Although

many well known companies has manufactured engines which are either performance

engines or fuel efficient engines. The main motto ofFUTURE ENGINES PVT LTD is to

develop an engine model with good fuel efficiency, high performance engines and most

importantly cost effective.

INTRODUCTION:

Perhaps the invention of engine or introducing the concept itself is considered as the most

scientific achievement in human history. In general, engine can be defined as a machine that

converts chemical energy of the fuel in the combustion chamber into mechanical energy thatis use to drive vehicles. As the time advances rapid development in automotive industry can

be noticed.

Automakers are keen in developing engines with high power, fuel efficient and with reduced

emissions these became the driving factor in the modern era. This is because of growing

pollution in atmosphere, depletion of fossil fuels and tough legislative norms laid by the

government. The concept of fuel saving has gained high importance in the present situation

,so automakers are concentrating on various new concepts like engine downsizing ,adding

superchargers or turbochargers for a smaller engine and achieving the performance of high

power engine with less fuel.

The fact is that automotive manufacturers are looking for alternate instead of the

conventional I.C. engines. Recently the usage of bio-fuels came into existence. HYBRID and

ELECTRICAL vehicles can be considered as the best alternative for conventional I.C

engines, these vehicles are very environment friendly. So manufactures are running parallel

which has both I.C. engine as well as the HYBRID/ELECTRIC engine in order to reduce the

emissions and to provide better fuel consumption.

Keep the latest trends in the automotive industry in mind ,our company has decided to design

a powerful engine with low fuel consumption ,compact ,light weight and most importantly

cost effective. We choose to use a naturally aspirated 4 cylinder engine to reach the targets

set by the manufacturers. With proper tuning of intake and exhaust, and with high

dimensional accuracy in modelling a engine components we are quite confident in achieving

the desired output.


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DESIGN TARGETS SPECIFICATIONS BY MANUFACTURER

SOURCE: FROM THE AUTO MANUFACTURERS


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ENGINE DESIGN METHODLOGY

To meet the design targets laid by the company. We choose LOTUS ENGINE

SIMULATION software is best approach to design an engine model because the software is

very user friendly, not a time consuming process to develop a model when compared to

remaining softwares, very cost effective (license cost is much low) and most importantly high

accuracy in the end results.

COMPANY ENGINE DESIGN SPECIFICATIONS AND JUSTIFICATIONS

ENGINE MODEL FE4

CYLINDER LAYOUT IN LINE 4 CYCLINDER

BORE*STROKE (mm) 86.5*85

DISPLACEMENT(L) 2 LT

COMPRESSION RATIO 14

FUEL SUPPLY PORT INJECTION

MEAN PISTON SPEED (m/s) 20

SPEED RANGE 1000-7000 rpm

JUSTIFICATIONS OF CHOSING THE VARIOUS DESIGN ATTRIBUTES FORTHE ENGINE MODEL:

1. BORE / STROKE RATIO: In this engine model we have chosen an oversquareengine which has larger valves in head cylinder, lower frictional losses (due to

reduced distance travelled during each engine rotation) and lower crank stress (due to

the lower peak piston speed relative to engine speed). Because of these characteristics

these engines are tuned to develop peak torque at relative speed and higher power at

relative speeds.[1]

BORE /STROKE = 86.5/85=1.017(B/S= 0.8 to 1.2 for small and medium sized engines). [2]

2. CONNECTING ROD: depending upon the formulaConnecting rod length = S*(1.8-2) = 85*2=170

3. COMPRESSION RATIO: In our design we decided to use compression ratio to be14:1, assuming that the engine has no effects with knocking (knocking is not

considered in this engine model). With higher compression with 14:1, few paper

reveal that better fuel conversion efficiency and volumetric efficiency is possible to

achieve, which results in improvement of fuel consumption.


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4. INTAKE RUNNER LENGTH: Is a part that supplies air/fuel mixture in to thecylinder evenly. The purpose of the runner is to take advantage of the Helmholtz

resonance property of air. In this engine model we chose to reduce the runner length

by 250mm from the plenum to the intake port because it is quite beneficial to have air

intake as fast as possible into the cylinders. By doing this we can increase the

turbulence and mixes with fuel and air better.[3] we choose to have intake pipe

diameter of 38 mm, to allow more amount air into the intake port. The intake port

diameter is chosen to be 37 mm because small diameter creates a pressure difference

(venturi effect) that effectively pumps the air into the cylinder.

5. INTAKE PLENUM VOLUME: The intake plenum volume was chosen to be 3.5litres, my understanding is that by having adequate volume for intake plenum, the

waves moves in ,lower their intensity by the time they reach the port of cylinder next

in firing sequence.

6. EXHAUST DIAMETER: The exhaust diameter has is very crucial because of theeffects of back pressure. Too much of back pressure has an adverse effecton the

engine performance as it restricts the flow rate of exhaust gases at higher RPM. Inorder to overcome that we introduced the exhaust diameter to be more (i.e. 40mm)

which reduces the flow velocity and also assists in scavenging of exhaust gases and

allows that fresh into the combustion chamber for the next stroke. We have chosen to

have the same pipe diameter (40mm) throughout the exhaust because in order to

reduce the pressure variations.

7. EXHAUST CATALYST: In this model we introduced a catalyst with a volume of 3litres thinking that sufficient space would be helpful in reducing the emissions.

8. VALVE LIFT :INTAKE VALVE LIFT: Intake valve lift is 8 which is derived by using a formula

LIFT = (IVO +IVC+180)/2= (15+60+180)/2=127.5 mmDEPENDING ON THE VALVE DURATION = LIFT /16=127.5/16= 7.967mm(8 app.)

Similarly exhaust valve lift =7.810 mm.


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VALVE TIMING DISPLAY:

The valve timing display is considered to be the crucial in determining the engine

performance. Our engine valve display is given below.

VALVE TIMING AND OVERLAPPING EFFECTS:

The reasons for choosing various valve timing and overlapping effects are explained below

VALVE

OPEN/

CLOSING

TIMING REASONEFFECT ON ENGINE

PERFORMANCE

INLET VALVE

OPENING

AT 15

BEFORE

TDC

THE CYLINDER PRESSURE

DOESNOT DROP EARLY IN THE

INTAKE SROKE

AT THIS POINT THE ENGINE

PERFORMANCE IS

INSENSITIVE

INLET VALVE

CLOSING

AT 60

AFTER

BDC

MORE VALVE TIME SO THAT

MORE CYLINDER PRESSURE CAN

BE ACHIEVED THAN MAN IFOLD

PRESSURE AT BDC.

PRINCIPAL FACTOR FOR

DETERMINING VOLUMETRIC

EFFICENCY

EXHAUST

VALVE

OPENING

AT 45

BEFORE

BDC

PROPER BLOW DOWN IS POSSIBLE

FOR EXPELLING EXHAUST GASES

TIMING OF EVO EEFECTS

THE CYCLE EFFICENCY

EXHAUST

VALVE

CLOSING

AT 25

AFTER

TDC

PRESSURE DOES NOT EFFECT THE

EXHAUST STROKE

HIGH POWER AT LOW SPEED

TORQUE AND IDLE

COMBUSTION QUALITY

SOURCE: JOHN B.HEYWOOD.INTERNAL COMBUSTION ENGINE FUNDAMENTALS.


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ENGINE DESIGN LAYOUT:

By using all design attributes we could design the engine in lotus .engine model is shown

below.

Source: engine model, LOTUS SIMULATION SOFTWARE.

RESULTS:

Finally, we obtain graphs fortorque vs. engine speed, power vs. engine speed, BSFC and

BMEP.

When we observe the torque curve with respect to the engine speed there is a gradual increase

in the torque. The graph shows that the peak torque is obtained at 4500 rpm which is 189.8

Nm. After the peak torque their subsequent downfall in torque when the engine reaches

maximum speed at 7500 rpm.

Similarly, when we consider the graph of power there is a significant increase with respect to

speed until it reaches the peak power at 6500 rpm which is 104.45KW and after the peak

power we can a notice a slight decrease in the power.

When a graph is plotted for B.S.F.C (g/KWHR), we can observe a slight increase in these

values at higher speeds. The average fuel consumption is very low thereby we can state that

the engine is fuel efficient.


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SPEED(RPM) POWER(KW) TORQUE(NM) B.M.EP(BAR) B.S.F.C(G/KW/HR)

VOLUMETRIC

EFFECINCY

(%)

1000 16.75 160 10.16 230.58 77.7

1500 25.83 164.46 10.44 230.57 79.8

2000 34.77 166 10.54 231.29 80.8

2500 44.89 171.45 10.88 232.87 84.1

3000 54.12 172.28 10.94 234.99 85.2

3500 64.15 175.03 11.11 237.39 87.5

4000 76.57 182.79 11.6 240.32 92.5

4500 89.44 189.8 12.05 243.1 97.1

5000 97.55 186.32 11.83 247.99 97.3

5500 102.4 177.8 11.29 255.84 95.7


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CONCLUSION:

We proudly say that FUTURE ENGINE PVT LTD has developed an engine which is fuel

efficient and powerful this can be determined from the graphs and value obtained. Therefore

it has reached all the optimum valves that are essentially required. Our company is successful

in designing an engine which is cost effective, reliable and most importantly simple to design.

We could successfully achieve all the targets that are 171NM AT 2500RPM, 189.8 NM AT

4500RPM, and 104.08 KW AT 6500 RPM laid by the manufacturers with a naturally

aspirated engine.

REFERNCES:

y JOHN, H. B., Ed. (1988). internal combustion engine fundamentals.y Jehad A.A yamin , M. H. D. (2003). "Performance simulation of a four stroke engine

with variable stroke length and compression ratio." applied energy 77: 447-463.

y Ceviz, M. A. (2007). "Intake plenum volume and its influence on the engineperformance, cyclic variability and emissions." Energy conversion and management48: 961-966.

y Prabhakaran Naganthan and Adrian martin, A. p., Australia Case study usingPISDYN of the effect on piston performance of using longer connecting rod.

y from http://www.custom-car.us/exhaust/default.aspx.y -Haggar, D. s. e. (1999). Internal combustion engine.y "Designing the cylinder head and valve train." from

http://www.metalstop.com/technical/eng-calc.shtml.

y http://auto.howstuffworks.com/question517.htm

6000 103.81 165.21 10.49 262.44 91.2

6500 104.08 152.91 9.71 272.93 87.9

7000 97.89 133.53 8.48 288.53 81.1

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