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Robbing a usable voltage from a Small engine flywheel.

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thudpucker

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I've asked this in the past. I don't think I made myself clear though.
Here's a drawing of the whole thing as far as I know it will be at this time.
The questions are plethoral!

The purpose of this Idea is to make an electrically operated Needle valve. The problem with most little Gas engines is the Needle valve sticking.
My Needle valve is going to be power both ways.

1. I have that big piece of Ferrite.
I thought if I wound some wire around each leg of the "E" I'd get a "LUMP" off each of the legs as the Ign magnet passed by the ends of the Ferrite. That would charge a Cap. (I don't know what kind and how much of a Cap)
Is that wrong?
Any hints on how to go about that? Thin wire, Thick wire? 10 turns or 200 turns?

2. Now look down at that Blue Circle around my Needle valve Solenoid.
Can I wire that coil to make it go both in and out under power very very quickly?

The Working RPM is 3500 which would cycle the Needle Valve about 900/minute.
I'll have to vary the length of the Needle pulse to make it work at 800Rpm (Idle) and 3500 Rpm(full throttle). I'll work on that later unless someone has the answer right now. Thank you if you do.

The Big Small engine companies have used a Large capacitor to re-start after the initial start up and run. My idea is for a 5 Hp Recoil start engine.
I'm fairly certain somebody by now has an invention like I have in mind and is working which might have me re-inventing the wheel. But I don't know of anybody doing it.

It's chilly now and I can't go to my Barn and enjoy myself. But If I can get some questions asked, I'll start on whatever I can do in the house.
 

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BradtheRad

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The few small engines I have worked on, as I recall, had a needle valve or two. But they didn't move around a lot. I adjusted it for best engine speed by turning it with a screwdriver, or my fingers.

I've been looking over images on the internet to refresh my memory. I don't see them needing a mechanism as you describe. The method of carburetion was a tiny hole in the throat of the intake passage.

But that doesn't mean there isn't some use for your idea. If you were to make the right amount of windings on the right kind of core... and then the right amount of windings on the needle valve.

I believe the E-shape core would create a multi-pole magnet. Perhaps it would make 3 pulses in a row. But that's subject to experimentation.
 

chuckey

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In the sort of needled carbs that I know - Solex and SU, the needle is "sucked" up by the vacuum. The volume on all carbs is set by the butterfly. Many carbs do not have needles = fixed venturi carbs, such as Weber. There is a case for altering the butterfly to maintain a constant speed as the load changes, but this is a butterfly control - often done by the pressure of the sump oil spinning against a plate, which backs off the setting spring.

Frank
 

dick_freebird

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Small engines typically had a magnet for the magneto
(newer ones, I dunno) and you could install a second
magneto to pick up power. However it will be fairly
limited current and high backing voltage, unless you can
shunt (rectify) it into a nice big reservoir capacitor.
There may be a substantial reverse spike too, which
might need snubbed or bridged. The magnetos have
the unfortunate property of having one end case-grounded
so bridge rectification is likely a no-go.

I don't think there is a whole lot of power there, probably
not enough to run a high impedance injector.

Needle valve sticking is a hygeine problem, not a
mechanical one. Why you want to fix "gum" with high
tech gizmo action, I don't get. Nor why you think a
highy speed cyclic moving needle valve is going to
fare better than a quasi-static one. From messing
with EFI for a while, I kind of doubt it - I've had
carbs last longer than injectors especially in bad
fuel quality situations.
 

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