Design Aspects & Possible Problems:Human power:
- What can an average human comfortably produce?
- Cadence (pedal RPM)
- 50-70 rpm (Ivan and Peter)
- 60 rpm (DIY Cycle Power website)
- Power
- 45-65 continuously (Ivan and Peter)
- 60-100 W continuously, 200 W at sprint (according to Barry)
- 75-200 W @ 12-25 V (Pedal-a-Watt Stationary Bike Power Generator website)
Frame Type:
Old
conventional bikes that can be quickly mounted and removed from the
system would be preferable over exercise bikes due to their ease of
portability (just ride them to the site!). They also usually have
higher quality bearings (less friction) and are more similar to one
another, allowing for a general, 'one size fits all' design.
Bike gears:
- Some bike gear ratio info:
- Bike 1 (mountain/road bike?): ratio max = 3.43, min = 0.74
- Crankset (front gears teeth count) = {28-38-48}
- Freewheel
(back gears teeth count) = {14-16-18-20-22-24-34}
- 700C wheels ~= 700mm o.d., 622mm bead seat diameter (part where the tire sits on the rims)
- Bike 2 (road bike) ratio max = 3.57, min = 1.5
- crankset max = 50, min = 42
- freewheel max = 28, min = 14
- wheel ~700 mm o.d.
Drive options:- belt-on-tire
- how to prevent slipping?
- adjustable distance between axises
- able to withstand greater axial forces
- tire directly on generator axle
- less surface area in contact -> more likely to slip?
- would it work with rough mountain bike tires?
- chain & sprocket, or gear to gear
generator/motor:- size?
- how much power can an average person produce?
- rpm required?
- can get higher RPM with belt around bike rim/tire (or tire directly driving generator shaft)
- example: 26 inch tire on 1 inch generator shaft => 26 x rpm increase
- bike will have certain amount of built-in gearing capability
- can use additional gearing if necessary
- Use old electrical motors as generators?
- Easier to get old electric motors (washer/dryer, fan, pump, etc)
- DIY
Cycle Power website has used old motors from washing machines and
magnetic tape spools. They suggest joining together the shafts of two
automotive electric fan motors (each produces a few watts, 12V)
- typical gas generators
- Scooter motors: See scooter_motor_datasheets.zip attachment for data sheets from a particular manufacturer (Shenzen Unite)
How to combine effort (to produce more power)- multiple generators on multiple bikes
- for direct power (no storage)
- could be an interesting project for a fourth-year elec student
- talk with professors, etc
- wikianswers: can you combine two generator circuits together?
- you can always combine generator circuits. The problem comes in with
HOW in phase the circuits are. If the generators are in phase (0
degrees apart) their AC voltages and currents would combine completely,
but if they are out of phase (90 degrees apart) the voltages and
currents will appose each other to such an extent that they will
basically cancel each other out. The trick is to apply some sort of
phase correction to one of the circuits in order to modify the phase
difference between the two so that you can get the desired power
output. Just be careful not to exceed your rated line currents when
combining two generator circuits, otherwise things could get smoky!
- store power to build up
- battery
- not as impressive for demonstrations
- low current -> long time necessary for charging?
- quick charge batteries possible?
- flywheel
- transmission necessary for combination
- different rotational speeds input
- multiple bikes, working single generator
- greater force, same RPM
- more power?
- stronger chain required?
- eliminates need for electrical/mechanical combination
- complicated building
- lots of welding necessary?
- series or parallel (back to front or side by side)
- side by side (parallel)
- everyone pedaling on a single axle
- series
- can weld together existing bike frames
- arrange according to size (ascending order?)
how to regulate generator power?- Can use a 2 A 12 V regulator to provide steady 12 V
- Careful not to surpass the max input voltage of the regulator, otherwise circuit will blow
- transformer?
- does it need a constant input?
- battery / large capacitor
- Buck-boost DC-DC converter
- Can handle variable input voltage
- Multiple outputs can be combined in parallel
- More efficient than a voltage regulator
- Requires design of switching circuit
- flywheel
misc:- materials
- welded steel (low grade pipe/tubing)
- likely to match that of old mountain bike frame
- aluminum tubing?
- rollers
- steel tubing (pretty cheap)
- bearing
- possible to make prototype structure out of wood?
- I don't see why not... especially if it uses a belt-on-tire design
- construction
- welding
- do we have someone who can weld?
- can we get some training?
- bolted connections
- could make collapsible for portability
Existing designs:
Human powered generators:
- SEF @ utoronto (c/o Barry Rawn)
- video of bike at work (http://esc.ele.utoronto.ca/~barry/calliope_bike.mov)
- We opted for a training stand, so that one could back up a regular
bicycle to the device with no alterations and use the generator. The
generator was a set of DC motors from an EV Warrior electric bike
retrofit kit: that meant they had both a suitable design RPM and power
rating. We just clamped them onto a board at about the right spot
underneath the training stand.
- We experimented with directly powering things and charging a battery.
Directly powering was most satisfying but producing steady power was
difficult.
- quick facts: in our system a person could produce 60-100W continuously
with reasonable effort and 200W at a sprint. We tried to make a bike
wheel into more of a flywheel by adding concrete- sucked. The final
configuration just powered a 110VAC cigarette lighter inverter. Very
easy to demonstrate typical appliances.. as long as they don't care
about being turned on and off. Unfortunately, it was difficult to pedal
at just the right pace required by whatever was hooked up. This is
because of the over and under voltage cutouts settings on the inverter;
if you pedaled too fast, power was cut off, and if you pedaled too
slow, same thing.
- DIY Pedal Powered Generator
- http://www.los-gatos.ca.us/davidbu/pedgen.html
- Welobike
- http://www.welobike.com/Site/Welcome.html
- http://www.facebook.com/group.php?gid=2416776454
- an organization dedicated to producing clean green energy to power the
lights for non-profit, government, and corporate organizations. Each
WeloBike can produce on average 50W/h of electricity (and upwards of
100W/h for experienced cyclists).
- bikes store power in batteries, one unit costs about $500-800
- article in the Toronto Star
- http://www.thestar.com/living/article/255823
- pedal-a-watt stationary bicycle generator
- http://www.econvergence.net/electro.htm
- U-Gen power storage system
- http://www.scienceshareware.com/bike_gen.htm
- similar bike-stand concept
- relies on belt around bike tire
- Windstream human power generator
- http://www.gaiam.com/product/eco-home-outdoor/green+living/emergency+preparedness/human+power+trainer.do?gcid=S18376x028&keyword=bike%20generator
- Most adults can generate a steady 75 to 150 watts with spurts of double that power.
- adjustable stand that raises and clamps the rear axle of bike
- with an adjustable friction wheel
- flywheel for steady power
- DC generator that can deliver over 500 watts.
- Youtube - bike generator
- http://www.youtube.com/watch?v=5EhllIuPjeI
- looks to have a fairly slow RPM
- large mass flywheel
- old exercise bike with flywheel, hooked up to alternator
- initially producing ~300 amps?
Bike Trainers (basically a stand with resistance rollers):- http://www.tacx.com/producten.php?language=EN&fl=true&lvlMain=16
- http://www.amazon.com/gp/product/B00145GGBW/ref=sr_1_8/105-5782206-4343601?ie=UTF8&s=sporting-goods&qid=1194153666&sr=1-8
- simple design, can probably be replicated using any material (even wood)
- David Butcher's training stand design
- http://www.los-gatos.ca.us/davidbu/pedgen/training_stand_generator.html
- generators were Razor Scooter 250 Watt motors
- material used
- trainer stand
- base: about 3 x 6 sheet plywood
- motor mount
- 2x2 boards
- screws, washers, etc
- hinges
- skateboard wheel for "pulley" (direct friction against bike tire)
- tensioned against bike tire with bungee cord/spring
- very simple design, easy to build, cheap materials
- not as efficient as a stand-alone generator, but okay for temporary
Prototype:
- use existing training stand (try to find cheap used one?)
- can then be used with any bike (BYO bike)
- stands very compact & portable
- can stand be used with 26 and 27 inch bike tires?
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ď scooter_motor_datasheets.zip (1781k) Peter Yu, Feb 9, 2009 5:43 PM
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