electronic govener for gas engine

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dacflyer
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electronic govener for gas engine

Post by dacflyer » Fri Feb 08, 2002 3:24 pm

i got a old gas engine / generator
the govener is non-repairable
( will not regulate properly )
is it possible to make a electronic governer for this engine using a servo ? and maybe the sensor will get info from the rpms or magneto pulse or flywheel magnet? , and i need to be able to adjust it to a certain rpm, approx. 3,600rpms
any info is helpful.. thanx

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Re: electronic govener for gas engine

Post by josmith » Fri Feb 08, 2002 4:33 pm

I saw a home made one with a solinoid working aginst a spring. It was actually a voltage regulator. It was tuned so that the coil would tend to close the throttle with higher voltage and the spring would open the throttle at higher voltage. Very simple and effective but it would take some trial and error to get it right.<p>Of course a stamp could easily read the rpm from a sensor and control an R.C. type servo directly to control the speed. Seems like overkill.<p>[ February 11, 2002: Message edited by: josmith ]</p>

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Re: electronic govener for gas engine

Post by josmith » Fri Feb 08, 2002 4:35 pm

That's open at lower voltage.

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Chris Smith
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Re: electronic govener for gas engine

Post by Chris Smith » Fri Feb 08, 2002 5:47 pm

That depends on How accurate you need to keep the generator, and the response time. 60 Hz is your aim but are you changing loads quickly? The easiest way to keep the motor spinning at a given rpm is very simple if the load stays fairly constant. All lawn mowers use them and they are called the "air governors". They place a movable arm or wing against the cooling fans output of wind, and based upon the rpm, a spring fights the wind coming off the fan and is equal and opposite to it, and in turn this places the throttle at a set point. If a load is placed upon the motor, the rpm drops and the spring that fighting the equal and opposite wind force, now forces the throttle open slightly more to compensate, and vice versa. As long as the variables aren't too great it is fairly accurate system, to less than 100 rpm overall accuracy. Done right you can get it to within one percent overall rpms. You also must incorporate a adjusting screw to set the unit up because changing the spring tension isn't practical.

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Re: electronic govener for gas engine

Post by dacflyer » Fri Feb 08, 2002 9:25 pm

yes, i know a lot about gas engines, but you will not find the air vain controled governers on a horizontal engine, the governers are internal with centrifical weights. the parts are no longer available for this engine, thats why i need a electronic version , i like to have something kind of accurate , the responce time can be as quick as the servo can function..but its no more critical than the responce time of a mechanical governer<p>[ February 09, 2002: Message edited by: dacflyer ]</p>

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Re: electronic govener for gas engine

Post by hlreed » Sat Feb 09, 2002 8:38 am

Those centrifigal govorners were developed for the first steam engines. Amazing. The speed regulator needs to sense rotary speed, so speed is an output. The throttle regulates speed, so it will be an input for your regulator. The units are different so you need to take that into account. RPM needs to be converted into throttle position. You have one more variable. That is you, the operator must set the RPM needed.
So you have:
engine RPM
Throttle position
RPM desired.
To make this easier, go digital. Get a count from RPM. Set a digital RPM. Move the throttle with a servo.
You need to compare RPM with your RPM and move the throttle with the difference.
Throttle = engineRPM - ORPM
This is your control system. Now you do not have to calibrate the throttle and your units are taken care of.
Is that any help?
Harold L. Reed
Microbes got brains

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dacflyer
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Re: electronic govener for gas engine

Post by dacflyer » Sat Feb 09, 2002 12:25 pm

i gives good ideas, but i have no idea how to make this , i was thinking a servo whould do the trick with, a controller to keep rpms fairly steady, even when a load is applied,it whould recover. i just don't have the brains to make such a controller...Hmmm

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Re: electronic govener for gas engine

Post by Chris Smith » Sat Feb 09, 2002 12:40 pm

If you want to go electronic that fine, and it will be no small job. However, air governor are on both horizontal and vertical models and you should make your own from a few levers, pendulum, and fine tension springs. It couldnt be simpler than this method and accuracy isn't going to be a big problem. But if you want to go digital etc, there is a article in this months N&V about a laser tach that will be your starting point. If you build this we can walk you into the next stage of how to convert that info into a output to drive your solenoid/ stepper assembly

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Re: electronic govener for gas engine

Post by dacflyer » Sat Feb 09, 2002 9:32 pm

Hmmm, this might not be as easy as i thought, this engin i have has a 90* offset carb, and i see no was to make a air type governer for this engine,, the origional governer was internal,,<p>i thought that maybe with the servo and a pickup
( hall sensor ) near the flywheel and some kind of simple controler of somesort,,, but laser? i think thats overkill,,Hmmmm

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Re: electronic govener for gas engine

Post by Chris Smith » Sat Feb 09, 2002 10:46 pm

All you need for the motor is a crude fan, one that pushes some kind of force. It doesnt have to be fancy. Two inches in diameter, four would be better. Be happy to draw a diagram for you. Ive been a mechanic and designer for better than 30 years. Real simple. <p>PS,.... hall sensors, LEDs, laser's, all require the sequencing, counting, divide by, and then the .... "send to"...... and then everything in reverse....... decode information, power the drivers, feed back loop , etc. Its not SIMPLE?<p>[ February 09, 2002: Message edited by: Chris Smith ]</p>

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Re: electronic govener for gas engine

Post by russlk » Sun Feb 10, 2002 10:55 am

If this is a 60Hz power generator, you already have the tach info. Compare that with a local 60 Hz oscillator in a exclusive OR gate. Amplifiy that to drive a solonoid. Send me your email address and I will send you a schematic. [email protected]

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Re: electronic govener for gas engine

Post by Ron H » Mon Feb 11, 2002 7:18 am

Russ, an XOR is a phase detector. I think he needs a frequency-locked loop, not a PLL. It would be damned difficult (and overkill) to phase-lock a gas engine that has a varying load. If I were to try to do this electronically, I would probably start with some sort of RPM sensor on the magneto or spark plug, apply that to an LM2907 frequency-to-voltage converter, amplify and filter the difference between its output and that of a voltage reference, and use the resulting error signal to pulse-width modulate a solenoid working against a spring, which would in turn control the throttle. The response time of the engine would have to be considered in the design of the loop filter, or you wind up with a gas-powered oscillator. Not a simple job.<p>Ron H

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Re: electronic govener for gas engine

Post by russlk » Mon Feb 11, 2002 9:24 am

You are right, Ron, if the PLL works there will be zero frequency error in the generator output. But, I anticipated the load problem and designed a logic frequency discriminator which will hold the frequency to +- 4Hz. It is sort of a bang-bang servo.

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Re: electronic govener for gas engine

Post by dacflyer » Mon Feb 11, 2002 11:23 am

oh boy,, what a can of worms..lol
this engin i have looks like either a wisconsion
or a techumsie...
( for give spelling errors please )
it is an old cast iron block engine rated about
5-7HP.i might have to opt for a home made mechanical version... but i see no room under the starter / flywheel housing for this,, most attach to the coil area, but i have no idea how i will mount one on this engine... i have seen them on
2 hp engines before, but thats it....
thanx anyway guys.......

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Re: electronic govener for gas engine

Post by hughesdevco » Mon Feb 11, 2002 12:28 pm

Hi there.......I've used an elctric govener from Military Generators..either 400 or 60 cycle will work .... you will have to do some mechanical modifications, as these are used on diesel engines...however it wil be installed to the linkage (also keep in mind they are 48 vdc) you can usually find these at a military surpluse store. I f you have a problem finding one, let me know & i'll ck here in Arizona where I buy most of my 'stuff'...good luck !!!!! Mel Hughes

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