Too cool! DIY bicycle with mechanical (flywheel) regenerative braking, assist (video)
 

I haven't even finished watching the 3 minute video and am posting it for its sheer awesomeness:



http://www.youtube.com/watch?v=shPgLBlBABc

More:

http://www.youtube.com/watch?v=BOnjtEKArXk

Basically what I was trying to Patent for cars starting in 2004, except the engine was capable of destroking itself and becoming a flywheel for energy storage and constant speed pulse and glide, using a CVT.

Another neat thing is the bike will stand up by itself if the flywheel is spinning fast enough. Just sit there with your feet on the pedals and wait for the light to change.

regards
Mech

Lets take it to another level.

Aero the bike so it coasts further.

While it is coasting keep pedalling just to spin up the flywheel.

Continue pedalling then add the stored energy in the flywheel.

This allows a burst of energy for acceleration to a speed higher than you could reach through pedalling alone.

Now you have the inverse of pulse and glide using stored energy to reach a higher average speed than you could on pedalling alone.

regards
mech

That thought crossed my mind too. As did: might be hard to turn corners if that baby is spinning really fast! :)

That thought also crossed my mind when I was trying to configure a vehicle with a large spinning flywheel with a mass of hundreds of pounds. In my mind the solution was to place the flywheel with it's axes vertical to the direction of travel of the vehicle.

The issue then becomes, how do you extract the energy from the flywheel without creating a yaw effect in the vehicle itself. I remembered my 37 Ford had to rods that ran lengthwise from the engine to points on the frame several feet back. This would tend to counteract the tendency for the vehicle to encounter yaw on acceleration.
I think that might be the best solution, but I never went far enough with the vehicle to actually test that theory in a real world application.

One thing I did think of when contemplating the effect on vehicle dynamics, was that having a large vertical axes mass in a moving vehicle would contribute greatly to stabilizing any pitching motion in the vehicle. Say you went over some railroad tracks or any other similar large undulation in the road. The gyroscopic effect of the large spinning mass would go far to eliminate any pitching, or up and down movements of the mass of the vehicle itself. Basically this means the vehicle would tend to stay level instead of the front and rear pitching up and down in relation to each other.

regards
Mech

Gah, I need access to a CNC mill and a lathe.

Cool. Very nice project.

Of course, the Flybrid system already works well, as demo'ed in Formula One. There are probably no fundamental principals that will change to diminish the high cost -- to get the speeds required for adequate energy storage, you end up with exotic stuff or a lot of weight.

Back in the late '90's I read in Mountain Bike Action magazine about a guy who welded a bike frame out of large diameter tubes and put an air pump/motor in one of the hubs. When braking the air was stored at higher pressure inside the airtight frame, then used to boost acceleration. Supposedly he was a teacher/professor and the bike was project for his students (but he was the one riding it:D).

...shades of the WWI Gnome engines! -- "snap" turn one direction but NOT the other (ha,ha).

On the plus side, if he just has to run into the corner store for a moment, he can hop off his bike and leave it standing on the sidewalk :D

If he just has to run into the corner store for a moment, he can "charge" it at home:D

Thought I would revive this thread.

In the bike the flywheel is rotating on the same axis as the frame. In the plane the axis was 90 degrees to the frame. It was the torque of the 350 pound rotating engine that allowed the plane to turn so quickly in one drection versus the opposite direction. The Fokker Dr1 could do a Flat turn, basically spinning on the axis of the engine with the rudder alone.

Spin a flywheel on a dinner plate, you can move it around easily while it is spinning vertically on the plate. You can even lift the plate rapidly until the flywheel is airborne and let it land on the plate, still spinning.

The flywheel resists changes in its plane of rotation more than any other.

That is why if horzontal or vertical It would resist leaning in either direction and allow the bike to stand vertically.

The rotary fighters of WW1 were wicked to fly. With engines weighing almost a third of the total weight of the plane and gobs of torque, they were inherently unstable and killed more pilots in training than combat. They would do 6 g turns and make pilots black out if they were not careful. Not bad for fabric, wood, and wires.

A horizontal spinning flywheel in a vehicle would also tend to make the vehicle stay level when encountering bumps or things like railroad tracks.

regards
Mech

One very big problem with the bike is it looks like there is NO freewheel between the wheel and flywheel. That means the flywheel STOPS when the bike stops. And it makes it VERY hard to accellerate unless you have already slowed down. You have to time the traffic lights and can not stop at stop signs.
Notice in the second video he cut out the start from a stop.

There needs to be a way to allow the flywheel to float at zero RPM until the first slowdown and to coast at high RPM at a stop. I also think it needs to be isolated from interference inside the wheel, though that will disrupt dynamics a lot versus the center of mass like his design.

To counteract some of the gyroscopic effects have 2 rotors spin up but in opposite directions. To make the CVT infinitely variable so it can be used from a stop insert a planetary gear set or power split device if you will. Look up IVT transmissions.
I was thinking of rigging up something like this in the trunk of my 2010 Prius working on the back wheels. The idea would be it would absorb the excess regen that the battery can't take and would supplement the acceleration when speeding up. This would allow those heavier on the brakes to capture more of the kinetric energy and the round trip efficiency would likely exceed the HV battery roundtrip efficiency. I'm also thinking about compressing nitrogen with a hydraulic gen/motor set up like Citroen in France are doing. For now it's just an idea.

It may be better, if more expensive, to connect the flywheel to a motor/generator and feed the energy in and out electrically, even at the size of storage required in an HPV.

That is how the Williams (F1 initially but now commercialized) and Porsche (which I think is using Williams' technology) work. The flywheel can then be sealed in a vacuum with magnetic bearings, the losses reduced and the flywheel run at higher speed.

I did find on the web (somewhere) reference to a university project where they had built prototypes that were about the size of a large coffee can. It didn't look to be too far beyond DIY either.

There was a Chrysler Sports Car Prototype (Le Mans) a decade or two ago that ran flywheel storage (with an LNG fuelled gas turbine). (It never raced.) That might be worth investigating to see how the gyroscopic effects were handled. The Chrysler Patriot - I think Reynard were involved on the engineering side.

Actually, given the power requirements in an HPV, chemical cell batteries are probably lighter and easier.

Color me dubious.

We all know, or should know, that it takes energy to propel a vehicle - any vehicle. So all energy stored in the flywheel is a product of the rider since there is no other source. If the rider doesn't initiate the pedaling, there's no energy stored. Even the downhill runs are ultimately a product of the rider - you have to expel 'human' energy to reach the top of the hill. Or if you expect to utilize the flywheel to assist uphill jaunts, then you MUST first input that energy into the flywheel BEFORE it can be extracted. There's no free lunch.

But more importantly, you need to consider the ADDITIONAL losses associated with the increased rolling resistance, and the added frictional losses in the rotating hardware - and lets not forget, the NuVinci CVP hub he's using is not very efficient (about 70% IIRC) and adds an additional 5.4 lbs to the total mass - in addition to the 15 lb flywheel. There's no shortage of 'flywheel' assisted bicycle patents.

We have spent decades pursuing efficient HPV's. The only way to improve upon it, is to lose weight, improve aerodynamics and make the gearing & tires more efficient. Bolting-on an additional 25lbs of mass & increased friction is not only counter productive, but an enormous waste of what precious little wattage the typical human is capable of.

Kenny, nobody said the energy from the flywheel was free. Its sole purpose is to store braking energy which would normally be wasted as heat.

Yes, adding all of that complexity would only hinder long distance biking, but may be worth its extra weight when catching and releasing energy in stop and go city traffic.

It's exactly the same as in hybrid cars: Motor/generators, batteries, fancy electronics do pay off in traffic, but not in steady highway driving.

I disagree - your motors & batteries are a secondary, independent source. The bike rider has no secondary source,.. only his/her legs. So where do think the energy comes from to resupply the energy used from the flywheel for multiple stops?

Prudent cyclists time 'lights' to minimize stopping - I do it daily... and have been for 50+ years.

I agree; you really try to avoid braking on a bike so the opportunities for energy capture are limited.

You might presumably use the flywheel as a power booster for acceleration after waiting at a light but, other than as a way of bypassing a power limit on electric motors for bicycles, I think electrical assistance with an externally charged battery will be superior.

Indeed :thumbup:

As just one intelligent example; how about a 4.2 lb. assist (that includes motor, drive hardware, controller and battery).

"One concern I do have is normally on my short 5 to 10 mile, 8 to 16� km errand runs I purposely do strong HP acceleration out of intersections and stop streets as a way to do mini interval training. If I use the assist for acceleration help, it is thrilling but in the long run I may be loosing muscle tone."

John Tetz's highly detailed build is here: www.recumbents.com/wisil/tetz/E-AssistMetric