Design Team # 3
Shell Eco Marathon
(Super-mileage Car)
Members:
Hussain Abdellatif
Sohaib Syed Alam
Julius Mantolino
Adam Procter
Supervisor:
Dr. Alex Kalamkarov
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2
Background
Scope
Design Requirements
The Design
Current Project Status
Future Considerations
Design Requirements Check
Budget
Acknowledgements
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Americas Shell Eco-Marathon Competition
not to go fast but to use least amount of fuel
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Houston, Texas – (March 29-April 1 2012)
2009 Dalhousie Team - 12th Place
(819mpg)
Core Super mileage Team with 4 volunteers
◦ Cover
◦ Steering
◦ Driver
3
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Ultimate Goal: Achieve ≥ 900 mpg
Qualify/Compete for Shell Eco Marathon:
◦ Geometric Limitations
◦ 4 stroke IC Gasoline Engine
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Increased Fuel Efficiency
Lighter Powertrain
Lighter Chassis
Lighter & More Efficient Wheels
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Engine
Fuel Injection System
Powertrain
◦ Transmission
◦ Bearings
◦ Clutch
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5
Chassis
Wheels
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Rolling Resistance
◦ Reduction in weight
◦ More efficient wheels
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Aerodynamics
◦ Reduction in frontal area
6
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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
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Parameter
35cc Honda[1] 35cc Subaru[2]
Weight [kg]
3.00
2.80
11.34
Displacement [cm3]
35.8
33.5
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1.3 @ 7000
1.6 @ 7000
5 @ 8000
1.6 @ 5500
1.76 @ 5000
4.6 @ 6500
0.43
0.57
0.44
Underpowered
N/A
Overpowered
Max. Power [HP @
RPM]
Max. Torque [Nm @
RPM]
Max. Power to Weight
Ratio [HP/kg]
Past Experience
Engine Selected : 35cc Robin Subaru
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50cc Yamaha[3]
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One-way Needle
Bearing
Reused electric
motor from Yamaha
Gear reduction
Requirement: Max. Noise Level <90 dB
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Stock Muffler:
◦ Lower Efficiency
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Glass Pack Muffler:
◦ Perforated Design
◦ Packing diffuses sound
◦ Less restriction
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Glass Pack Muffler [4]
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Possible fuel delivery methods:
◦ Carbureted
◦ Port Fuel Injection
◦ Direct Injection
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Direct Injection is not Viable:
◦ Requires mechanical fuel pump (competition
rules)
◦ Complex
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Carburetor
Port Fuel Injection
Advantages
 No cost
 Time savings
Advantages
 Controlled amounts of fuel
Disadvantages
 Low efficiency
 No control on optimum fuel
consumption
 Conversion kit can be readily
purchased
Disadvantages
 Cost (~$800)
 Needs pressurized system
 Calibration and fine tuning
Selected: Port Fuel Injection
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Replace carburetor
Conversion kit purchased from Ecotron:
Key components:
◦ Oxygen (O2) Sensor
◦ Fuel Injector
◦ Programmable Engine Control Unit (ECU)
◦ Fuel Pressurization System
◦ Throttle Body
Sensors – Input
Throttle Position
Inlet Air Pressure
Inlet Air Temp.
Engine Kill Switch
Controlled Output
Engine Control Unit
(ECU)
Programmable
Control
Parameters
Spark Timing
Fuel Injector
Crankshaft Position
Exhaust Temp.
Exhaust O2
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Control parameters as required
Fuel Pressurization System [5]
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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
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Calculate suitable gear ratio:
◦ 𝑉𝑎𝑣𝑔 = 15 𝑚𝑝ℎ = 6.71 𝑚/𝑠
◦ 𝜔𝑤ℎ𝑒𝑒𝑙,𝑎𝑣𝑔 = 19.17
◦ 𝐺𝑅 =
16
5000
183
≅ 28
𝑟𝑎𝑑
𝑠
= 183 𝑅𝑃𝑀
Direct Drive
Variable Transmission
Advantages:
 Simple design
 Cheap
 Lightweight
Disadvantages:
 Can’t run at BEP
 Start-up load
Advantages:
 Vary the gear ratio to the wheel
 Change torque at wheel
Disadvantages:
 Expensive
 Complicated and heavy
 Requires gear shifting
Transmission Type Selected : Direct Drive
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Components:
◦ Gear Reduction Method
 Two Stages
◦ Bearing
◦ Clutch
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
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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
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Planetary Gearbox for 1st stage
Roller Chain and Sprockets for 2nd stage
Ceramic (Si3N4) Ball Bearings [6]
Steel Bearings
Advantages:
Advantages:
 Significantly reduced weight;
 Cheap
(0.5 x steel)
 30% the friction of steel
 Provides smoother operation
Disadvantages:
Disadvantages:
 Expensive (10 x price of steel)
 Heavier
 More friction
 Requires lubrication
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Bearings Selected : Ceramic Ball Bearings
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Centrifugal [7]
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Friction Plate [8]
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Friction Plate Clutch
Centrifugal Clutch
Advantages:
Advantages:
 Flexibility in engaging
 Light weight
 Less power losses
 Compact
 Greater torque capacity
 Automatic engagement
Disadvantages:
Disadvantages:
 Heavier
 Power losses during slippage
 Space
 Spares
 Risk of stalling
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Clutch Selected : Centrifugal Clutch
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Engine is not overloaded
Torque@ Clutch Vs. Car Speed
Power@ Clutch Vs. Car Speed
(with G = 20)
1.00
0.90
0.80
0.50
0.70
Power (hp)
Torque @ Clutch (Nm)
0.60
0.40
0.30
0.50
0.40
0.30
0.20
0.20
0.10
0.10
0.00
0.00
0.00
10.00
20.00
Car Speed (mph)
25
0.60
30.00
0.00
10.00
20.00
Car Speed (mph)
30.00
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Design Requirement: Lighter chassis
◦ Aluminum Alloy 6061-T6
◦ Yield strength = 275 MPa
Past team
• 1’’ OD by 0.125” thick
• Cross section area = 0.34 in2
Selected
• 1-1/4’’ OD by 0.065” thick
• Cross section area = 0.24 in2
 30% weight reduction per unit length
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Weight estimate entire car (with driver) ~
90kg
Withstand static load of 700N on roll bar
Max. Stress: 55 MPa
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Max. Stress: 75 MPa
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Max. Stress: 50 MPa
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Max. Stress: 43.8 MPa
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3 wheels: 2 in front, 1 in back
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Front Wheel Design
◦ Lighter
◦ No Internal Ratchet
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Back Wheel Design
◦ Internal Ratchet
◦ Heavier
Back vs Front Wheel Assembly [9]
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3 wheels: 2 in front, 1 in back
Past team
• Front Wheels:
o
Small (406 x 44c)
• Back wheels:
o
Small (406 x 44c)
o
Back Wheel Design
Selected
• 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
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Incorporate Sprag Clutch in Back Wheel
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Disc Brakes:
◦ Reusing from past team
◦ Consistent brake performance
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Hubs & Spokes
to be purchased
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Past:
◦ Michelin road tires
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Selected:
◦ Continental GatorSkin tires
◦ Higher inflation pressure
Michelin Tires [10]
 150 psi vs. 60 psi
 Lower rolling resistance
◦ Flat and puncture resistant
◦ Durable
GatorSkin Tire [11]
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Purchased:
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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
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Achieved Already
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Qualify/Compete for Shell Eco Marathon
◦ Geometric Limitations
◦ 4 stroke IC Gasoline Engine
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Lighter Powertrain (Centrifugal)
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Lighter Chassis (30% reduction)
To Be Achieved:
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Increased Fuel Efficiency - to be confirmed with dyno
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Lighter & More Efficient Wheels
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Achieve ≥ 900 mpg - TBD
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Assemble Power Train
Assemble Power Train, Steering & Cover onto
Chassis
Purchase Wheels & Wheel Components
Obtain Engine Curves with Dyno:
◦ Carburetor
◦ Fuel Injection
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Fine Tune ECU Programmable Parameters
Dyno Vehicle @ Wheels
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Engine
$425
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Fuel Injection System
$586
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Drivetrain & Clutch (estimate)
$2000
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Chassis
$500
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Wheels
$2500
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Total (15% Contingency) ~
$7000
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
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We Thank Our Sponsors
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[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/PR
D~5005-157/continental-ultra-gatorskin-700-x-28-wire-tire.jsp
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Engine Specs
Load Torque Assumptions
Bearings
Bearing, Output Shaft FEMS
Starter Assembly FEM
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𝑇𝑙𝑜𝑎𝑑,𝑤ℎ𝑒𝑒𝑙 = 𝑇𝑟𝑜𝑙𝑙𝑖𝑛𝑔 + 𝑇𝑑𝑟𝑎𝑔

𝑃𝑙𝑜𝑎𝑑,𝑤ℎ𝑒𝑒𝑙 = 𝑇𝑙𝑜𝑎𝑑,𝑤ℎ𝑒𝑒𝑙

𝑇𝑟𝑜𝑙𝑙𝑖𝑛𝑔 = 𝑟𝑤 (𝐶𝑟𝑟 𝑚𝑔)
𝑇𝑑𝑟𝑎𝑔 = 𝑟𝑤 (0.5𝜌𝐶𝐷 𝑉 2 𝐴)
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𝐶𝑟𝑟 = 0.005 +
1
𝑝
𝑉
𝑟𝑤
0.01 + 0.0095
𝑉 2
100
◦ 𝑝 − 𝑡𝑖𝑟𝑒 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑖𝑛 𝑏𝑎𝑟𝑠
◦ 𝑉 − 𝑐𝑎𝑟 𝑣𝑒𝑙𝑜𝑐𝑡𝑖𝑦 𝑖𝑛 𝑘𝑝ℎ
𝐶𝐷 = 0.4 [ref] – common CD used in old 90’s cars
𝑚 = 150𝑘𝑔 - the max. allowed in competition
𝑟𝑤 = 0.35𝑚
𝐴 = 0.343 𝑚2 - frontal area of around (19inx28in)
𝜌 − 𝑎𝑖𝑟 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑜𝑓 1.181 𝑘𝑔/𝑚3
𝑝 = 130 𝑝𝑠𝑖 = 8.96 𝑏𝑎𝑟𝑠
Torque Load @ Wheel Vs. Car Speed
7.000
6.000
Torque (Nm)
5.000
4.000
Roll
3.000
Drag
2.000
1.000
0.000
0.00
5.00
10.00
15.00
Car Speed (mph)
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20.00
25.00
30.00
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0
𝑇𝑐,𝑚𝑎𝑥
𝑇𝑐 =
𝑇𝑐,𝑚𝑎𝑥
𝑇𝑒
𝜔 ≤ 𝜔𝑒 − 𝑐𝑎𝑠𝑒 1
𝜔 > 𝜔𝑒 , 𝑇𝑒 > 𝑇𝑐,𝑚𝑎𝑥 − 𝑐𝑎𝑠𝑒 2
𝜔 > 𝜔𝑒 , 𝑇𝑒 < 𝑇𝑙𝑜𝑎𝑑 − 𝑐𝑎𝑠𝑒 3
𝜔 > 𝜔𝑒 , 𝑇𝑒 < 𝑇𝑐,𝑚𝑎𝑥 − 𝑐𝑎𝑠𝑒 4
𝑇𝑐 < 𝑇𝑓,𝑚𝑎𝑥 − 𝑐𝑎𝑠𝑒 5
𝑇𝑐,𝑚𝑎𝑥 = 𝑛𝑟𝑜 𝜇𝑚𝑟𝑠 𝜔2 − 𝜔𝑒 2
𝑇𝑓,𝑚𝑎𝑥 = 𝑛𝑟𝑜 𝜇𝑝𝑚𝑎𝑥 𝐴
𝑚 = 48.15 g, 𝑛 = 2
𝑟𝑜 = 38.6 𝑚𝑚
𝑟𝑠 = 24.9 𝑚𝑚, 𝑐 = 1 𝑚𝑚
𝜇 = 0.25, [ref]
𝑝𝑚𝑎𝑥 = 1030 𝑘𝑃𝑎 [ref]
𝐴 = 0.0015 𝑚2
𝑇𝑓,𝑚𝑎𝑥 = 21 𝑁𝑚
Slip
Period
Max. Clutch
Torque
Engagement
speed
Clutch “Bites”
Clutch transmits
engine torque
Ceramic (Si3N4) Ball Bearings
Steel Bearings
Advantages:
Advantages:

Significantly reduced weight; density of

Cheap
Si3N4 is 3.2 g/cm3 versus 7.8 g/cm3 of steel

Better impact loading handling

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
Disadvantages:

Disadvantages:
Expensive (10 times the cost of steel

Heavier
bearings)

Higher co-efficient of friction

Need for lubrication

More vibrations and rocky operation
Ball Bearings Selected : Ceramic Ball Bearings
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