Flywheel

[nwguy]

Anyone here ever dabble with flywheels for energy storage? I'm pondering adding a flywheel to a bike made from an additional 27" bike wheel with added weight at the rim. I could see a v-belt connecting the bike's rear wheel to the flywheel that tightens and loosens via a brake lever. Engage to slow down and spin up the flywheel, disengage while at a stop to let the flywheel spin, reengage to accelerate away from the stop. The flywheel's spokes would need to be shielded with disks for safety and efficiency reasons. Think of it like regenerative braking with hybrid cars. Will post pics when I build a prototype.

 

[andyinchville1]

HI,

That is an interesting idea....I wonder if using something smaller than a 27" wheel would be good tho....I mean...would putting 27" wheel on a bike be a little ungainly in terms of size?....Where would it go?....I would be very interested in seeing some sketches...

I like the idea of assisted starts to avoid having to pedal first before letting off the clutch or having to excessively slip the clutch...

Good thinking outside the box!

Andrew

 

[nwguy]

See linked image. I'm thinking over the back wheel and along side, with v-belt pulleys mounted on the hub flange like motorized bike cogs are, so the pulleys are aligned.

The bigger diameter the wheel the more effective the flywheel action would be. The wheel should be light, except for at the perimeter where the weight would be. Note that the wheel in the linked image is a 26" mountain bike wheel as opposed to a skinny, lightweight wheel.

 

[andyinchville1]

Hmmm....Interesting.....I wonder how many RPM's do you see that additional flywheel wheel turning?...I suppose for additional weight the tire could be filled like a tractor tire (liquid) but I don't know how many RPM's would be safe....Your idea of steel is good too....just make sure it is balanced well....But then again....Hmmm another thought....Would all that weight over on one side of the bike make for awkward handling?

Maybe a smaller diameter but heavy "dumbell" looking flywheel assembly could be built
and tucked down low by the bottom bracket / kickstand area....Advantage there would be down low for lower center of gravity / better handling, small diameter means less gyroscope effect (maybe affects handling in a negative way?), and dumbell design means equal weight on both sides of the bike....Just random thoughts late at night ;-)

I like the idea of a belt drive to spin up the flywheel wheel....Simple yet effective!

 

[Happy Valley]

Horizontal

http://video.google.com/videoplay?docid=-5591140509449393106

oe vertical?

A vertical flywheel would create gyro wobble on a two wheeler, no?

 

[Smerf]

I was just wondering about this a couple of days ago when I was watching an F1 replay.


What were you thinking of using as a clutch between the flywheel and the normal driveline?

 

[SirJakesus]

I'm guessing that this would add stability to a bike too and possibly fight you a little on turns. I had heard about this kind of thing before and I have always wondered why kinetic energy isn't put to better use more often. I can't wait to see what you come up with!

 

[nwguy]

Interesting video. There are actually a few if you search for "pedal flywheel" on YT. The bigger the flywheel the lighter it can be. Seem to be a few trade offs. Have you ever held a bike wheel by the axle and had someone spin it fast, and then tried to wobble it around? Your normal bike wheels have lots of gyroscopic stability, but either they don't have a negative effect on handling, or we're all used to it as part of the package. I think you could only do a horizontal flywheel with a trike, so I'll attempt a vertical arrangement. I thought about mounting a couple of lead scuba weights on opposing sides of a wheel, well balanced and very well secured. Or maybe bending a piece of rebar around the rim. For the engagement mechanism I've got some v belt pulleys and idlers that I plan to use. The idler would push in and out via a cable and tighten and loosen the belt. The weight on one side would be negligible compared to many motor assist arrangements where the whole motor is way off to one side. Certainly not as bad as having one loaded pannier over one side of the rear wheel.

 

[kerf]

Aside from starting off, couldn't the same thing be accomplished with a super heavy rear wheel? At speed it would store energy and be much simpler. In any event, the energy in a pedal driven flywheel would cost more effort than it gives.

 

[nwguy]

Well, that's the point isn't it? Starting off.

The idea is to store the energy that would normally be wasted by braking, and use it for accelerating. You wouldn't want to make your vehicle keep going when you want to slow down.