electronic govener for gas engine

[hlreed]

You sure you cannot repair the old centrifigal govorner? Nothing on it should break. If the shaft from the engine is broken, it will not turn and will not regulate. Can you look at it?<p>By the way guys, an eight bit subtraction is 256 parallel XOR operations. A = x - y is a universal control system. If everything was numeric, you could substitute a thermostat control from the hardware store.

[Chris Smith]

The air governor sounds better by the minute? The PLL is frequency driven but it is too accurate and you would need at least two preceding and two lagging the center spot to keep a center frequency. A small plastic fan off any electric motor would work for your "Air Governor", real simple, and no reinventing the wheel!

[dacflyer]

the shaft that held the centrifical weights in place,, the casing is worn out, and will not hold the shaft no more...maybe i might decide to use this engine on a go-cart Hmmmm
thanx anyway guys...

[Ron H]

Harold said:<p>"By the way guys, an eight bit subtraction is 256 parallel XOR operations. A = x - y is a universal control system. If everything was numeric,
you could substitute a thermostat control from the hardware store."<p>OK Harold, I'll bite:

(1) Since when does 8 bit subtraction require 256 XORs?<p>(2) Can you really get a thermostat from the hardware store that accepts numeric inputs?<p>Ron H

[Chris Smith]

The Air Governor is not a centrifugal Governor by the way, Its far simpler.

[toejam]

I would get a clean 5volt pulse from the ignition circut that you can feed into the gate of a mosfet that is logic driven and is in series with a soloniod and a regulated power source-the duration of the pulse (either the on or off time of it can be used) to form a pulse width modulated power regulator that determines how hard the soloniod pulls against a spring that tries to hold the throttle open or closed.Once you have adjusted the power applied to maintain the frequency desired, it should be pretty consistant.

[toejam]

I would get a clean 5volt pulse from the ignition circut that you can feed into the gate of a mosfet that is logic driven and is in series with a soloniod and a regulated power source-the duration of the pulse (either the on or off time of it can be used) to form a pulse width modulated power regulator that determines how hard the soloniod pulls against a spring that tries to hold the throttle open or closed.Once you have adjusted the power applied to maintain the frequency desired, it should be pretty consistant.

[Ron H]

Toejam, you have just (re)invented an electronically controlled throttle. It will work fine until the load on the engine changes. What's missing is a feedback loop which compares the engine RPM (or generator frequency) with a reference, amplifies and filters the error, and modulates the throttle to minimize the error.<p>Ron H

[toejam]

Ron,
I said a regulated power supply.If the supply to the mosfet is constant and i think a seven horsepower generator should be able to provide 5-6watts of power necessary to operate that supply,once it is up to its working speed,as far as i can see,the only variable will be the rpm of the system which the mosfet/soloniod should be able to control untill it is overloaded to the point the throttle can't increase the torque necessary to keep it going.Up untill then,the spring tension against the soloniod should be the only referance needed.I may have missed something here though.
tj

[Ron H]

Toejam, what provision have you made for increasing power to the throttle solenoid when the load on the engine increases? In the absence of a governor, a throttle simply provides (relatively) constant fuel flow at a given setting. As the load on the engine changes, the fuel flow requirements change. A governor (mechanical or electronic) provides this feedback.<p>Ron H

[toejam]

hi Ron,
Thr pulses coming out of the ingition primary or secondary circut shound be a direct function of the r.p.m of the engine.Lets say we are using a 12 volt regulated power supply to supply the mosfet.The clean pulse would best be provided by a one shot that fires for a predetermined amount of time each time the ignition system is triggered.A 555 should do that nicely a few turns wrapped around the spark plug wire's insulation may even be enough to trigger it.The amount of time the pulse to the mosfet lasts can than be easaly adjusted using a pot.Once this has been estiblished,a solonoid can be chosen with sufficient pull to operate the throttle against a spring.By tweaking the spring tension and pulse length, the rpm of the engine should become a function of the spring tension and pulse width.The amount of torque supplied will than increase or decrease according to the load, but rpm's should be pretty constant.
tj

[Ron H]

I apologize, Toejam. I totally missed the part about the pulses coming from the ignition sysyem. I agree that you should be able to get speed regulation from this type of system. The degree of regulation, I guess, would be dependent on the mechanical advantage built into the solenoid/spring/throttle linkage.<p>Ron H

[toejam]

apolagy accepted although certianally not neccessary Ron. Thanks for making me add the 555 to give a fixed pulse width I doubt it could have worked (if it will) without that.
tj

[DICKEYBIRD]

Here's my 2 cents worth:<p>Try http://www.emsjomar.com/ I have an R/C model aircraft twin engine syncronizer from Jomar and it works great. If memory serves, he once had a "Cruise Control" for R/C aerobatic aircraft that would keep the engine at a preset rpm via the throttle servo and a magnet/hall effect sensor. I checked the site and he doesn't have it listed but drop him an email and see what happens! He's a great guy.<p>Milton Dickey

[Dean Huster]

The automatic choke on my old 1979 F-250 crapped out and a manual choke conversion was going to be too ucky to install to suit me (knob would have to be in the center of the dash to reach). Then I got the great idea to use a stepper motor to manually control the choke where the circuit would reset and pull the choke fully open when the ignition was turned on and then let me turn a simple knob to adjust the choke. Choke by wire.<p>Then I went to sleep that night and woke up refreshed and a lot smarter.<p>Still, I love the idea of electronic control of an engine like that. Gotta be PID. None of this PLL or bang-bang comparator stuff. Really, with a LM2907, it would work just like the temperature controller on a crystal oven only pull in the spring-loaded solenoid.<p>Or you could work in an A-D converter and use a stepper motor ..... <p>Dean