High Efficiency Moped A MQP Proposal Submitted to the Faculty of the WORCESTER POLYTECHNIC INSTITUTE in partial fulfillment of the requirements for the Degree of Bachelor of Science in Mechanical Engineering by ___________________________________ Tim Ellsworth Date: 10/11/2012 Approved: Prof. Kenneth Stafford, Major Advisor Prof. Cosme Furlong-Vazquez Table of Contents List of Tables ................................................................................................................................................. 4 List of Figures ................................................................................................................................................ 5 Abstract ......................................................................................................................................................... 7 Executive Summary ....................................................................................................................................... 9 Introduction ................................................................................................................................................ 12 Objective ................................................................................................................................................. 12 History ..................................................................................................................................................... 13 Component Selection .................................................................................................................................. 16 Specifications .......................................................................................................................................... 16 Specifications Defined ............................................................................................................................. 16 Engine...................................................................................................................................................... 21 Gasoline (two-stroke vs. four-stroke) ................................................................................................. 21 Diesel ................................................................................................................................................... 21 Electric Motor ..................................................................................................................................... 22 Propane/Natural Gas .......................................................................................................................... 22 Selection .............................................................................................................................................. 23 Drive Train ............................................................................................................................................... 30 Harmonic Drive ................................................................................................................................... 31 Jack Shaft............................................................................................................................................. 33 Single Stage Spur gear and chain combination ................................................................................... 34 Compound reverted and chain ........................................................................................................... 34 Planetary Gear Train ........................................................................................................................... 35 Engine to Planetary ................................................................................................................................. 37 Dog Clutch Mechanism ........................................................................................................................... 38 Dog Clutch ........................................................................................................................................... 39 Belt ...................................................................................................................................................... 39 Friction Disc ......................................................................................................................................... 39 Basket .................................................................................................................................................. 40 Electronic ............................................................................................................................................ 40 Band Brake Planetary .......................................................................................................................... 40 Pneumatic ........................................................................................................................................... 40 1 Centrifugal ........................................................................................................................................... 40 Freewheels .............................................................................................................................................. 40 Bicycle ..................................................................................................................................................... 41 GMC Denali ......................................................................................................................................... 42 Roadmaster Granite Peak ................................................................................................................... 42 Design .......................................................................................................................................................... 44 Preliminary Designs................................................................................................................................. 44 Design Iteration 1 ................................................................................................................................ 44 Design Iteration 2 ................................................................................................................................ 46 Design Iteration 3 ................................................................................................................................ 48 Design Iteration 4 ................................................................................................................................ 51 Engine plate ........................................................................................................................................ 55 Final Design ............................................................................................................................................. 56 Controls ............................................................................................................................................... 56 Support Brackets ................................................................................................................................. 60 Engine to Gearbox Chain System ........................................................................................................ 64 Dog Clutch ........................................................................................................................................... 69 Manufacturing ............................................................................................................................................ 70 Manual .................................................................................................................................................... 71 CNC .......................................................................................................................................................... 76 Design for Manufacturability .................................................................................................................. 77 Results and Testing ..................................................................................................................................... 78 Robustness Testing ................................................................................................................................. 78 Motor mount movement .................................................................................................................... 78 Planetary output sprocket failure ....................................................................................................... 78 Motor to crank derailment and alignment problem .......................................................................... 79 Improperly installed 3/8 drive shafts .................................................................................................. 81 Engine to Planetary Issues .................................................................................................................. 81 Failure of #25 1:1 chain ....................................................................................................................... 82 Power Estimation ...................................................................................................................................