Secondary "hole shot" torque source

[KCvale]

Hi all, I'm new to here but not to web forums, I run several http://KCvale.com

This seemed like a good topic for my current project which is a totally green go cart "hole shot" torque burst system.

Some of you may remeber quite awhile back a guy that mounted a huge flywheel under his car (pinto I think) and when he hit the brake it spun the flywheel up, when he released the brake the enery was released back to the drive train.
Hence, instant torque boost.

Great idea, just a really poor brake torqe saving medium.
I have a design I'm working on that is so simple and elequent that for a go-cart it should only add about 10 lbs to the cart and provide a huge torque boost from that 0 to 5 MPH acceleration range, maybe as much as double, and every time for free.

What I am concerned about is gear ratios and clutches for this secondary system.

I'm buying a used 3-5 HP good ole Briggs and Straton clutch/chain single back wheel drive cart so the other back wheel is just free spinning.

I know I need the wheel size and torque output numbers to make any any useful gearing calculations, I am just wondering if anyone in this forum is interested in helping with this project.

 

[SloS13]

instead of engineering all of the parts for what you're talking about, why not get a bigger motor?

Sure a heavy flywheel could get you more power off the line once the clutch engages but you'll take a performance hit thereafter.

That is, unless you could somehow dynamically change the rotating mass of the flywheel.

 

[Pyrotechnic]

Have you heard of the Harbor Freight 6.5 HP engines ?

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96549

They are just so cost effective. An new overhead valve motor (Honda clone) with 6.5HP for $140, and sometimes much cheaper when on sale. All the Honda performance upgrades and parts work with these too.

 

[newrider3]

instead of engineering all of the parts for what you're talking about, why not get a bigger motor?

Sure a heavy flywheel could get you more power off the line once the clutch engages but you'll take a performance hit thereafter.

That is, unless you could somehow dynamically change the rotating mass of the flywheel.

From what I can tell he is talking about using a system with a completely separate flywheel from the engine.

 

[Pyrotechnic]

In theory it sounds like a good idea.....but as far as successfully executing it...that sounds really complicated. As far as I can think in the most primitive form, you would need a need a clutch and an extra limb to control it, most likely your left foot. That would really mess you up when you had to drive a manual transmission car though.

I suppose you would just let the clutch out when braking to spin up the flywheel, push the clutch in when stopped, then pop the clutch so the flywheel gets the kart going again. Thats one way I could think to do it. You would want to gear it so the flywheel is spinning very fast in relation to the wheel, that way it's going to provide lots of braking force, but it's also going to produce lots of torque when you pop the clutch on take off.

As far as that ratio, it's hard to say whats optimal. It's not like a motor where there's a redline, so in theory, the faster you can get it to spin in relation to the wheel, the better off you are.

 

[KCvale]

Sorry I was a little vauge.
Using a big flywheel was a poor example of the concept.

I want to capture all of the torque wasted by friction braking by using the force required to wind a big spring as the braking force and saving that force, then releasing it back out to the wheel as a super whallop of instant (free) propolsion torque.

My plan is to mount a Garage Door torsion tension spring, .262 gauge x 2" diameter x 35" long right wind, on a shaft directly beneth the rear axel.

By replacing the otherwise free spinning right back wheel with a sprocketed wheel I can gear and chain it to the spring.

I think that by simply tieing into the brake cable and adjusting it so the the first 1" or so of hand brake lever movement engages the "wind the spring" braking force before it moves on to friction braking if needed, and that covers that ease of use.

For releasing the boost I'll leave that to the operator with a simple cabled thumb lever on the steering wheel to enage the boost, but the obvious use is for that 0 to 10 mph acceleration range.

I am choosing a cheap 3.5 HP 4 cylinder go cart base because of it's extremely poor low end acceleration characteristics.

If my crude assesments so far prove out in real life, hiting the gas and boost at the same time at slow speeds or even at a dead stop would launch you up to speed like a slingshot, and contunually recharge itself every time you hit the brake even a little so it's ready again.

What is a torsion spring?
You have seen them in action in those windows shades you pull down with brute force to close, and when you release them they go flying up in a second and spin around.
Same thing, except the brute force to wind it is slowing your rolling cart wheel, and on release it goes back to the wheel.

Things to think about...

Unlike a gas engine that has an initally low torque output until it reaches ideal RPM's, this device is the opposite, it delivers full torque instantly and torque force is reduced as the spring unwinds.

To keep things simple for now...
What do figure would be a good distance to shoot for, like the first 10', 20' for the boost to cover in the setup above to give the 4 stroke motor a chance to rev up and take over at it's optimum rpm?

 

[847]

well first you need a proper gear, not all ratios will give you 15 mph+. efficiency is accomplished by getting more out of the device as opposed to how much you are putting in.... the only way you can get it to give you a solid take off, and a longer take off, is haevier flywheel and a spring that can hold more power. now, only way to spin the fly wheel and get tension in the spring is by putting it on a very hi ratio ( i.e 6:1 ) wich will result in lower output rpm, but maybe if the spring has enough in it, it can help boost that, plus the motor will be helping too. also, if you stored it ( the energy ) after you parked it and the next morning, press the button, and pop the clutch ( if you have manual belt clutch ) and just start your cart right up with no pulls .... i think i like your idea a little more now

edit, i just realized that it is powered by the deceleration of the motor ..... nice ..... and still possibly start motor without doing work .... ( providing you have good traction. ) i say have two rollers go on each wheel, on the rubber part, the wall. and have them BE the break, hook roller rod to a gear, turn the gear horizontal and hook up like a differential & power the fly wheel that way .... but how to release the fly wheel ..... i mean if you never released it, the rollers would either stick and wear uneven and rub the tire ... or cause spring to break ( one way to release fly wheel lol ) now, i'm not sure on how the release would work, BUT i suggest hooking it up to an input only ratio to the rear axel, ( like a bike, how it only spins one way ) and set it real high ratio so it will have grunt. like even if the gear only helps you 20 mph, a 20 mph gear is usually a pretty high ratio

 

[KCvale]

I'm not sure what part of this being a completly seprate system from the motor you don't understand...
No flywheels, minimal gearing, and stand alone operation via a completly differnt wheel than the motor driven wheel.

How can I clear this point up better?

 

[847]

another wheel? the system i described would not be connected to the motor either ( hence why i said an input device only the axel would be spinning and the gear would not spin up the fly wheel but the fly wheel could spin up the tires, and the motor )

 

[KCvale]

The original design is for a single rear wheel drive (static axel) cart with a free spinning opposite rear wheel, and putting a gear on that for the wind (brake), unwind (boost) system.

I am working on a live rear axel (2 wheel drive) plan now and it looks to be easier to do.
It is much easier to explain with pics and I amworking on some now that will make things clear.

Thanks for all the help so far!

 

[I like karts]

The way I see it, if you charge and release the spring, you'll end up going backwards

 

[jr dragster T]

Dude just get a snowmobile engine with the CVT clutch you will have tons of torque. Although you have a good idea but realisticly the chances of it working are slim.

 

[I like karts]

yeah

 

[ed1380]

hybrid go-kart. lol sounds fun. i mean green