Larger/Heavier Flywheel?

[LostCause]

Originally Posted by boxchain

I was thinking about this today and it hit me...two clutches. One between the engine and flywheel, and the other between the flywheel and driveshaft. When you want to glide or stop, disengage both To start the engine, engage the engine one. Prob have to use a hand lever or grow another leg

Consider this prior art (for any patent searches)

You are almost describing an inertia starter. An inertia starter doesn't receive energy from the engine/drive wheels, but it's entirely practical.

When you kill the engine and slow down, the inertia starter engages and gets up to speed. When stopped, an electric motor keeps the flywheel at speed...topping it up. When the engine is started, a clutch engages the inertia starter and turns over the engine.

I do like the elegance of your method of keeping everything inline. I was thinking of a starter replacement, but then you incur the weight penalties of two flywheels.

[boxchain]

One of these days I will invent something before someone else does

Oddly enough, google Ecomatic and this forum is on the first page.

Interesting about the motor keeping the flywheel topped up. I wonder how much energy would be lost while sitting at a stoplight...

[Chris D.]

What is P&G?

what is it used for and can it be done on any vehicle?
Does it help with FE?

please explain..

I'd like to add techniques to my FE roster, but I cant get past all these abbreviations.

[LostCause]

Originally Posted by boxchain

Interesting about the motor keeping the flywheel topped up. I wonder how much energy would be lost while sitting at a stoplight...

Depending on the bearings, I'd bet a pretty marginal amount. That just went in line with my inertia starter idea: a small-diameter flywheel (i.e. low stored energy) and small motors already in place for initial spin-up/engine starting.

Just thinking about the inline case, how would the flywheel be supported? I suppose it could freewheel on an axle passing through the transmission and engine. Don't clutches completely decouple the engine and transmission? I suppose I should look that up...

Originally Posted by Chris D.

What is P&G?

P&G stands for "Pulse and Glide"...a technique pioneered on hybrids. It works best on cars whose engines can easily be killed (hybrids, manuals). Automatics have a tougher time because shift points can't be controlled, torque converter losses are high, and the engine can't be placed into neutral/killed easily.

Since engines operate most efficiently near peak torque, the pulse is a quick acceleration up to about 10mph above the desired cruising speed. Immediately, the engine is either killed (ideally), the car put into neutral (ideally), or simply allowed to coast with the engine on. The coast lasts until the car is about 10mph below the desire cruising speed, where the engine is bump started and the "pulse" cycle starts again. This pattern repeats indefinately.

If done correctly, you can see huge gains. I don't know exact numbers, but I would expect a 10%+ increase in fuel economy.

- LostCause

[LostCause]

Originally Posted by boxchain

One of these days I will invent something before someone else does

Looks like VW beat you too it...

From: greatchange.org

Originally Posted by VW 1L

A specially developed starter-alternator makes sure the engine is immediately restarted. Positioned between the engine and gearbox and using a dual clutch system, this works as both current generator and flywheel. In gliding mode, both clutches are open. When the driver presses the accelerator pedal again, the clutch between the engine and the starter-alternator is closed, causing the still turning flywheel to restart the engine without consuming any electrical current.

- LostCause

[Funny]

That would be an engineering nightmare . A heavier flywheel, however, would increase inertia (only to a certain point,) allowing easier (more efficient) driving in hilly terrain, but a loss in fuel consumption if using for hypermiling (EOC). It is a trade off most people cannot afford. Stick with the stock flywheel and don't change to heavier or lighter. If you must change, heavier is the better choice.

[Arminius]

UK flywheel project: http://www.greencarcongress.com/2008...d-in.html#more

[JoJotheTireMan]

Originally Posted by Frank Lee

I think it could be a benefit if accompanied by way high gears- should be able to "lug" better without jerking. And/or it could allow much earlier shifting or better skip shifting.

Also from same user: "I like the idea because I don't coast that much anymore; it's just too dang annoying. What I can use every time, P&G or not, is the ability to grab higher gears sooner. And it seems on my car the limiting factor to how low of an rpm I can lug at is flywheel mass, because if I go too low it bucks. "

Sorry for the manual quote, I couldn't figure out how to multi-quote.

The point here is Frank Lee is 100% correct here.

I used to race 2 stroke dirt bikes in endurance style woods racing and one of the hot tricks back then was to add flywheel weights to gain that much needed low end grunt that most 2 strokes lack, it made the bike much better for woods racing. It resisted stalling, eliminated bucking, and added low rpm grunt, which allowed you to lug 3rd instead of screaming 2nd through the same obsticle. The trade off is slower revving. Which in my application was perfect, and many of the racers back in the 80s and 90s used this trick on 2 strokes.

I, like the rest of the world, switched to the 4 stroke bikes and would never go back. They just put the power down better, again more low end grunt (useable power) and less high rpm hp (drag race power).

Just thought I would add my 2 cents worth from my own experience with flywheel weight. JoJo

[JohnnyGrey]

The only way this would help your car is if it allows you to maintain a very low idle (~500rpm). Otherwise you're wasting more power in the city. You need more fuel to put the same power to the ground, and on every shift, you have to wait for that flywheel to spin down before letting out the clutch (unless you want a jerky ride).

[guitarterry]

I have also been reading about this flywheel subject. My two cents, weight will hurt economy, no way around it. BUT a engine designed with a heavy flywheel might get great gas milage. Eg. a 440 big block in a 69 charger with a super light flywheel will probably get worse gas mileage than xfi metro with a super heavy flywheel. does that prove that a super heavy flywheel is fuel efficent NO. It is just that the design need a heavy flywheel for some reason. (maybe drivability)