Design Team # 3 Shell Eco Marathon (Super-mileage Car) Members: Hussain Abdellatif Sohaib Syed Alam Julius Mantolino Adam Procter Supervisor: Dr. Alex Kalamkarov 2 Background Scope Design Requirements The Design Current Project Status Future Considerations Design Requirements Check Budget Acknowledgements Americas Shell Eco-Marathon Competition not 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 3 Ultimate Goal: Achieve ≥ 900 mpg Qualify/Compete for Shell Eco Marathon: ◦ Geometric Limitations ◦ 4 stroke IC Gasoline Engine 4 Increased Fuel Efficiency Lighter Powertrain Lighter Chassis Lighter & More Efficient Wheels Engine Fuel Injection System Powertrain ◦ Transmission ◦ Bearings ◦ Clutch 5 Chassis Wheels Rolling Resistance ◦ Reduction in weight ◦ More efficient wheels Aerodynamics ◦ Reduction in frontal area 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 7 Parameter 35cc Honda[1] 35cc Subaru[2] Weight [kg] 3.00 2.80 11.34 Displacement [cm3] 35.8 33.5 49 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 8 50cc Yamaha[3] 9 One-way Needle Bearing Reused electric motor from Yamaha Gear reduction Requirement: Max. Noise Level <90 dB Stock Muffler: ◦ Lower Efficiency Glass Pack Muffler: ◦ Perforated Design ◦ Packing diffuses sound ◦ Less restriction 10 Glass Pack Muffler [4] Possible fuel delivery methods: ◦ Carbureted ◦ Port Fuel Injection ◦ Direct Injection Direct Injection is not Viable: ◦ Requires mechanical fuel pump (competition rules) ◦ Complex 11 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 12 13 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 14 Control parameters as required Fuel Pressurization System [5] 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: ◦ 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 17 18 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 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 20 21 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 22 Bearings Selected : Ceramic Ball Bearings Centrifugal [7] Friction Plate [8] 23 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 24 Clutch Selected : Centrifugal Clutch 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 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 26 Weight estimate entire car (with driver) ~ 90kg Withstand static load of 700N on roll bar Max. Stress: 55 MPa 27 Max. Stress: 75 MPa 28 Max. Stress: 50 MPa 29 Max. Stress: 43.8 MPa 30 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] 31 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 32 Incorporate Sprag Clutch in Back Wheel Disc Brakes: ◦ Reusing from past team ◦ Consistent brake performance 33 Hubs & Spokes to be purchased Past: ◦ Michelin road tires 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] 34 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 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 37 Assemble Power Train Assemble Power Train, Steering & Cover onto Chassis Purchase Wheels & Wheel Components Obtain Engine Curves with Dyno: ◦ Carburetor ◦ Fuel Injection 38 Fine Tune ECU Programmable Parameters Dyno Vehicle @ Wheels Engine $425 Fuel Injection System $586 Drivetrain & Clutch (estimate) $2000 Chassis $500 Wheels $2500 -------------------------------------------- 39 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 40 We Thank Our 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/PR D~5005-157/continental-ultra-gatorskin-700-x-28-wire-tire.jsp 42 43 44 Engine Specs Load Torque Assumptions Bearings Bearing, Output Shaft FEMS Starter Assembly FEM 45 𝑇𝑙𝑜𝑎𝑑,𝑤ℎ𝑒𝑒𝑙 = 𝑇𝑟𝑜𝑙𝑙𝑖𝑛𝑔 + 𝑇𝑑𝑟𝑎𝑔 𝑃𝑙𝑜𝑎𝑑,𝑤ℎ𝑒𝑒𝑙 = 𝑇𝑙𝑜𝑎𝑑,𝑤ℎ𝑒𝑒𝑙 𝑇𝑟𝑜𝑙𝑙𝑖𝑛𝑔 = 𝑟𝑤 (𝐶𝑟𝑟 𝑚𝑔) 𝑇𝑑𝑟𝑎𝑔 = 𝑟𝑤 (0.5𝜌𝐶𝐷 𝑉 2 𝐴) 46 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) 47 20.00 25.00 30.00 48 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 49 50 51