Senior Design Notebook
Columbia Vector Technologies Senior Design Group 8
1
Index
Project selection, 1
Bicycle with a Continuously Variable Transmission, 5
Smart-scale Hydrogen Generator, 5
Smart Roof using PVDF, 6
Project selection decision, 7
Faculty feedback, 8
Faculty feedback response, 8
Literature review, 9
Patent, 9
Literature, 9
Internet, 9
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3
4
Sep. 25th, 2018
Project selection
Proposal 1: Bicycle with a Continuously Variable Transmission
Pros: purely mechanical project, interesting and practical
Cons: slightly difficult to make, high rate of failure
Mission of the project: The goal of this project is to create a CVT to be retrofitted
onto a bicycle. Currently one bicycle CVT transmission exists but it isn’t largely
commercially available and is very heavy. We plan to effectively retrofit a bicycle with
our CVT hub and create an interface for the rider to see live updates about bicycle
status.
Proposal 2: Smart-scale Hydrogen Generator
Pros: If successful, will be a great way for energy conversion
Cons: potential safety hazards, not very related to mechanical engineering
Mission of the project: The proposed project is to create a small-scale hydrogen
generator, roughly one cubic foot in size. Motivation for this project lies within the fact
that electrolysis is a well understood phenomenon, however, is not often effectively
used within small scale devices which offers several distinct benefits. Some of these
5
benefits include portability, long term storage of energy, and the ability to store
energy which would otherwise be lost if not used ie. wind and solar.
Proposal 3: Smart Roof using PVDF (Polyvinylidene fluoride or polyvinylidene
difluoride)
Pros: easy to make. Some existing experience with the material
Cons: Project might be too easy.
Mission of the project: This project aims to create a porous-polymer based scalable
model for a smart roof that has tunable optical transmittance and can be used to
switch between opaque and transparent states. Unlike the traditional electrochromic
glass technology which is already commercially available, the smart roof we are
proposing does not need any energy input to remain at either of the two states.
We are not really seriously considering this project
6
Oct. 12th, 2018
Project Selection Decision
Based on the advice from many of the TAs and the professor, we have chosen to
pick the first project, designing a CVT for bicycles.
Some bottlenecks of the CVT project
1. The CVT design itself is quite a difficult problem. Cannot use current CVT
design on cars, since it has slipping and does not work well for applications
with high torque and low RPM. Also, the current CVT design is too bulky.
2. Other challenges that arise from the first bottleneck, that need to be
considered, are that of transmission size and placement. All of the outlined
design options above are relatively complex systems requiring various moving
parts which will require considerable space. A bicycle provides significant
packaging constraints due to being a very narrow two-wheeled vehicle that
needs to be maintained under a certain weight.
3. Picking a bike (?). Should not be that much of a trouble.
7
Oct, 23rd, 2018
Faculty feedback
Below are some feedbacks from faculty members in the department
Myers/Lipson: This is a fun project. I think it is challenging, but doable. Though I do
know that the CVT bandin the car requires an extremely difficult manufacturing
technique to pull out all of the ductility of the material.
We are probobaly not going to copy the CVT designs are cars. This may need some
creativity, however, we are trying to make a brand new CVT design
Stolfi:This was successfully attempted a long time ago. The difficulty was gear ratio
which was very low. If their CVT is just 2 cones with a belt between them, it is difficult
to get high gear ratios.Variation in cone diameter is limited if it has to fit in a bicycle
frame. For bicycles, high gear ratios are required. A novel design is required (which
may be possible).
This further makes us sure that we cannot use a traditional cone design for the bike
CVT.
8
Nov. 7th, 2018
Literature Search Results
Patent:
We can only find car CVT patents on the internet (Google Scholar). The CVT uses
traditional V pulleys. (No. 881925A)
Internet:
Nuvinci CVT, sun and planatary gears. More information at:
https://www.fallbrooktech.com/nuvinci-technology
https://www.youtube.com/watch?v=kN8CCY1vFC8
Scientific journal:
Rockwood, D., Parks, N.,Garmire, D. (2014). A continuously variable
transmis-sion for efficient urban transportation.Sustainable Materials and
Technologies, 1-2, 36-41.doi:10.1016/j.susmat.2014.10.002
Link: https://www.sciencedirect.com/science/article/pii/S2214993714000049
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