design team # 3 shell eco marathon ( super-mileage car)

Design Team # 3Shell Eco Marathon (Super-mileage Car)

Members:Hussain Abdellatif Sohaib Syed AlamJulius Mantolino

Adam ProcterSupervisor:

Dr. Alex Kalamkarov

Background Scope Design Requirements The Design Current Project Status Future Considerations Design Requirements Check Budget Acknowledgements

Outline

2

Americas Shell Eco-Marathon Competitionnot to go fast but to use least amount of fuel Houston, Texas – (March 29-April 1 2012) 2009 Dalhousie Team - 12th Place (819mpg) Core Super mileage Team with 4 volunteers

◦ Cover◦ Steering◦ Driver

Background

3

Ultimate Goal: Achieve ≥ 900 mpg Qualify/Compete for Shell Eco Marathon:

◦ Geometric Limitations ◦ 4 stroke IC Gasoline Engine

Increased Fuel Efficiency Lighter Powertrain Lighter Chassis Lighter & More Efficient Wheels

Design Requirements

4

Engine Fuel Injection System Powertrain

◦ Transmission◦ Bearings◦ Clutch

Chassis Wheels

The Design – Our Scope

5

Rolling Resistance◦ Reduction in weight◦ More efficient wheels

Aerodynamics◦ Reduction in frontal area

The Design -Challenge

6

Direct Fuel Consumption Options Considered:

◦ Old 35cc Honda◦ Old 50cc XF Yamaha ◦ New 35cc Robin Subaru

Honda 35cc [1]

Robin Subaru 35cc [2]

50cc XF Yamaha

Engine

7

Parameter 35cc Honda[1] 35cc Subaru[2] 50cc Yamaha[3]

Weight [kg] 3.00 2.80 11.34

Displacement [cm3] 35.8 33.5 49

Max. Power [HP @ RPM]

1.3 @ 7000 1.6 @ 7000 5 @ 8000

Max. Torque [Nm @ RPM]

1.6 @ 5500 1.76 @ 5000 4.6 @ 6500

Max. Power to Weight Ratio [HP/kg]

0.43 0.57 0.44

Past Experience Underpowered N/A Overpowered

Engine Selected : 35cc Robin Subaru

Engine - Selection

8

One-way Needle Bearing

Reused electric motor from Yamaha

Gear reduction

Engine Modifications-Electric Starter

9

Requirement: Max. Noise Level <90 dB

Stock Muffler:◦ Lower Efficiency

Glass Pack Muffler:◦ Perforated Design◦ Packing diffuses sound◦ Less restriction Glass Pack Muffler

[4]

Engine Modifications-Muffler

10

Possible fuel delivery methods:◦ Carbureted◦ Port Fuel Injection◦ Direct Injection

Direct Injection is not Viable:◦ Requires mechanical fuel pump (competition

rules)◦ Complex

Fuel Delivery System

11

Carburetor Port Fuel Injection

Advantages No cost Time savings

Advantages Controlled amounts of fuel Conversion kit can be readily

purchasedDisadvantages Low efficiency No control on optimum fuel

consumption

Disadvantages Cost (~$800) Needs pressurized system Calibration and fine tuning

Selected: Port Fuel Injection

Fuel Delivery System-Selection

12

Replace carburetor Conversion kit purchased from Ecotron: Key components:

◦Oxygen (O2) Sensor◦Fuel Injector◦Programmable Engine Control Unit (ECU)◦Fuel Pressurization System◦Throttle Body

Fuel Delivery System-Electronic Fuel Injection

13

Control parameters as required

Engine Control Unit (ECU)

Throttle Position

Inlet Air Pressure

Fuel Injector

Inlet Air Temp.

Exhaust Temp.

Crankshaft Position

Engine Kill Switch

Programmable Control

Parameters

Sensors – Input Controlled Output

Exhaust O2

Fuel Delivery System-Electronic Fuel Injection

14

Spark Timing

Fuel Pressurization System [5]

Fuel Delivery System-Pressurization

15

Transmits power from engine Require minimum power losses Provide sufficient torque Best Efficiency Point (BEP) ∼ 5000 RPM

◦ Provided by bsfc curve◦ To be verified with testing

Calculate suitable gear ratio:

Powertrain

16

Direct Drive Variable Transmission

Advantages: Simple design Cheap Lightweight

Advantages: Vary the gear ratio to the wheel Change torque at wheel

Disadvantages: Can’t run at BEP Start-up load

Disadvantages: Expensive Complicated and heavy Requires gear shifting

Transmission Type Selected : Direct Drive

Powertrain- Transmission

17

Components:◦Gear Reduction Method Two Stages

◦Bearing◦Clutch

Powertrain

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Roller Chain Timing Belt Planetary Gearbox

Advantages: Easy to design Cheap

Advantages: Cheap Light weight

Advantages: Compact Design High reliability

Disadvantages: Weight Large sprockets Space

Disadvantages: Pulleys sizes Space

Disadvantages: Cost (~$800) Medium Weight

Primary Stage Selected : Planetary Gearbox

Powertrain – 1st Stage

19

Planetary Gearbox for 1st stage Purchase Neugart PLE60-20 Planetary

Gearbox from Wainbee Ltd.◦ 94% efficient◦ 20:1 gear ratio◦ Continuous torque 44 N.m.

Roller Chain and Sprockets for 2nd stage

Powertrain - Overall

20

Planetary Gearbox for 1st stage Roller Chain and Sprockets for 2nd stage

Powertrain - Overall

21

Powertrain - Bearings

Ceramic (Si3N4) Ball Bearings [6] Steel Bearings

Advantages:

Significantly reduced weight;

(0.5 x steel)

30% the friction of steel

Provides smoother operation

Advantages:

Cheap

Disadvantages:

Expensive (10 x price of steel)

Disadvantages:

Heavier

More friction

Requires lubrication

Bearings Selected : Ceramic Ball Bearings22

Centrifugal [7]

Friction Plate [8]

Powertrain-Clutch

23

Powertrain-Clutch Selection

Friction Plate Clutch Centrifugal Clutch

Advantages:

Flexibility in engaging

Less power losses

Greater torque capacity

Advantages:

Light weight Compact

Automatic engagement

Disadvantages:

Heavier

Space

Risk of stalling  

Disadvantages:

Power losses during slippage

Spares

Clutch Selected : Centrifugal Clutch24

Powertrain-Torque Calculations

Engine is not overloaded

0.00 5.00 10.00 15.00 20.00 25.00 30.000.000.050.100.150.200.250.300.350.400.45

Torque@ Clutch Vs. Car Speed (with G = 20)

Car Speed (mph)

Torq

ue @

Clu

tch

(Nm

)

0.00 5.00 10.00 15.00 20.00 25.00 30.000.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

Power@ Clutch Vs. Car Speed

Car Speed (mph)

Pow

er (

hp)

25

Design Requirement: Lighter chassis◦ Aluminum Alloy 6061-T6◦ Yield strength = 275 MPa

Weight estimate entire car (with driver) ~ 90kg

Withstand static load of 700N on roll bar

Chassis-Selection

Past team Selected• 1’’ OD by 0.125” thick• Cross section area = 0.34 in2

• 1-1/4’’ OD by 0.065” thick• Cross section area = 0.24 in2

30% weight reduction per unit length

26

Chassis – Rear Loading

Max. Stress: 55 MPa

27

Chassis – Side Loading

Max. Stress: 75 MPa

28

Chassis – Pull Loading

Max. Stress: 50 MPa

29

Chassis – Push Loading

Max. Stress: 43.8 MPa

30

Wheels

31

3 wheels: 2 in front, 1 in back

Front Wheel Design◦ Lighter◦ No Internal Ratchet

Back Wheel Design◦ Internal Ratchet◦ Heavier

Back vs Front Wheel Assembly [9]

3 wheels: 2 in front, 1 in backWheels

Past team Selected• Front Wheels:

o Small (406 x 44c)• Back wheels:

o Small (406 x 44c)o Back Wheel Design

• Front wheels:o Larger (700 x 25c)

• Back wheels:o Larger (650 x 25c)o Front Wheel Design

Front Wheel Assembly:• Lighter

Larger Rim Size:• Less Bearing Loss

32

Incorporate Sprag Clutch in Back Wheel

Disc Brakes:◦ Reusing from past team◦ Consistent brake performance

Hubs & Spokes to be purchased

Wheels

33

Past:◦ Michelin road tires

Selected:◦ Continental GatorSkin tires◦ Higher inflation pressure

150 psi vs. 60 psi Lower rolling resistance

◦ Flat and puncture resistant◦ Durable

Wheels

Michelin Tires [10]

GatorSkin Tire [11]

34

Wheels

35

Purchased:◦ Robin Subaru 33.5cc engine◦ Electronic Fuel Injection (EFI) kit◦ PLE60-20 Planetary Gearbox◦ Aluminum tubing for chassis

Designed:◦ Power Train Components◦ Electric Starter Assembly◦ Chassis Main Frame Body

Project Status

36

Achieved Already Qualify/Compete for Shell Eco Marathon

◦ Geometric Limitations◦ 4 stroke IC Gasoline Engine

Lighter Powertrain (Centrifugal) Lighter Chassis (30% reduction)To Be Achieved: Increased Fuel Efficiency - to be confirmed with dyno Lighter & More Efficient Wheels Achieve ≥ 900 mpg - TBD

Design Req. Check

37

Assemble Power Train Assemble Power Train, Steering & Cover

onto Chassis Purchase Wheels & Wheel Components Obtain Engine Curves with Dyno:

◦ Carburetor◦ Fuel Injection

Fine Tune ECU Programmable Parameters Dyno Vehicle @ Wheels

Future Considerations

38

Engine $425 Fuel Injection System $586 Drivetrain & Clutch (estimate) $2000 Chassis $500 Wheels $2500--------------------------------------------- Total (15% Contingency) ~ $7000

Budget

39

We would like to thank: Dr. Julio Militzer Dr. Alex Kalamkarov Albert Murphy Mark MacDonald Angus MacPherson Peter Jones Allison Chua, Drew Moores, Ryan Louie &

Dainis Nams

Acknowledgments

40

We Thank Our Sponsors

Acknowledgements - Sponsors

41

[1] http://robinamerica.com/pspecsheet [2] http://www.baileysonline.com/itemdetail[3] http://www.elsberg-tuning.dk/yamaha.html[4] http://auto.howstuffworks.com/muffler5.htm[5] http://poisson.me.dal.ca/~dp_09_15/docs/Fall%20Build%20Report.pdf[6] http://www.vxb.com/page/bearings/CTGY/CeramicBallBearings[7] http://auto.howstuffworks.com/clutch1.htm[8] http://auto.howstuffworks.com/clutch1.htm[9] http://www.qbike.com/cgi-bin/find.cgi?st=road+wheel[10] http://www.michelin.ca/[11]

http://www.mec.ca/AST/ShopMEC/Cycling/TiresTubesWheels/RoadTires/PRD~5005-157/continental-ultra-gatorskin-700-x-28-wire-tire.jsp

References

42

Questions ?

43

Engine Specs Load Torque Assumptions Bearings Bearing, Output Shaft FEMS Starter Assembly FEM

Back Up Material

44

Engine Specifications

45

[ref] – common CD used in old 90’s cars - the max. allowed in competition - frontal area of around (19inx28in)

Torque Calculations (1)

46

Torque Calculations (2)

0.00 5.00 10.00 15.00 20.00 25.00 30.000.000

1.000

2.000

3.000

4.000

5.000

6.000

Torque Load @ Wheel Vs. Car Speed

RollDrag

Car Speed (mph)

Torq

ue (N

m)

47

Torque Calculations (3)

= 48.15 g,  

, , [ref] [ref]

Engagement speed

SlipPeriod

Max. Clutch Torque

Clutch “Bites” Clutch transmits engine torque

48

BearingsCeramic (Si3N4) Ball Bearings Steel Bearings

Advantages:

Significantly reduced weight; density of

Si3N4 is 3.2 g/cm3 versus 7.8 g/cm3 of steel

Co-efficient of friction is 30% that of steel

Less lubrication required Can operate at

higher speeds (20% to 40% higher)

Smoother operation because modulus of

elasticity higher (stiffer) than steel; 320 GPa

vs 200 GPa – less deformations leading to

less vibrations

Advantages:

Cheap

Better impact loading handling

Disadvantages:

Expensive (10 times the cost of steel

bearings)

Disadvantages:

Heavier

Higher co-efficient of friction

Need for lubrication

More vibrations and rocky operation

Ball Bearings Selected : Ceramic Ball Bearings

49

Power Train Stresses

50

Starter Mount Stresses

51