Electric governor

[dubbleUJay]

Now this is nowhere near a working model, but just to give an idea of what I'm thinking and there IS flaws in the design as well, just before I get some "flack" for those 
I need to get the op-amp to work on a single rail supply, +12Vdc, not 12-0-12 as in the cct.

[BruceM]

WJ,
I think there's going to be a lot more involved than just feeding the DC motor voltage to a comparator, then a mosfet to a solenoid.  This is going to be unstable.  Part of the problem is that the rpm is not constant due to compression and then ignition strokes. The real rpm looks like a hump.  The DC motor output will have to be filtered, as this is hardly clean DC.  The flywheels lag the engine response so much that an oscillatory situation is assured.

It might be possible to do this, using an op amp computed rpm velocity and acceleration terms for dampening.  I have such a circuit that I designed for another application attached. A massively filtered alternator output is the "flywheel" in the circuit shown.  A standard regulator would oscillate, because of the phase lag of the huge filter inductor.

I noted that the DC motor to solenoid device was promoted before it was developed, and then was not sold due to liability issues.  Yet the design was not released, nor any performance data ever provided. Hmmm.

Learn to program, it's not hard.  The Pixaxe chips are a perfect way to do so with very little expense.

Bruce

[dubbleUJay]

Hi BruceM,
I get what your saying about the oscillation, but is it not this oscillation of the cct that will make it work?
The lag of the flywheels and the small RPM difference the secondary spring will apply, is the key in this design I think.
I can see problems though if the voltage out from the DC motor is minute for say 650RPM & 655RPM, then this difference should be amplified to get a bigger "window" 

I would think that some filtering would have to be incorporated, but maybe just a crude 10-100pF cap for high frequency spikes from the brushes and a 1-10uF for a "reservoir" on the input from the DC motor.

I'll have to wrap my head around this a bit more, like I said, I'm no expert with this stuff

dubbleUJay

[BruceM]

The oscillation is going to be caused by the slow response of the flywheel; the system as proposed has no dampening.  The oscillation will only be limited by the authority of the solenoid. To make this abortion work, you'll have to add dampening of the applied correction based on the change in rpm, per the op amp circuit I provided. 

There would be no CCT to the solenoid, a 12VDC solenoid was specified.

It seems insane to me to use a DC motor for an RPM signal, when the rpm signal is already present in the AC waveform. Why add a mechanical problem?  AC signal frequency to analog voltage level could be done in some simple analog circuitry, but it is much easier and simpler to use a single chip computer like the Picaxe 08M or 14. Dampening of correction based on change in RPM is also easily done.

Best Wishes,
Bruce M

[dubbleUJay]

I can probably use my "copy" of National Instruments LabVIEW program and connect my Lister via a appropriate interface to my PC.
Their excellent tutorials will get me up and running in no time to control my speed with an actuator, but when my farmer brother over in Ireland sees this one day and he wants to make one, he'll have no clue of where to begin!

Enough sarcasm from my side , I think it boils down to simplicity for me and the ability for some ordinary Joe to reproduce it in the future. The latter being the main reason.
A micro controller would be better, but then I might as well do a total automation project and I'm just not up to it at this stage.
For now, my Lister CS has a "lazy governor" under maximum load and I just want to assist the mechanical governor with a little extra tension electro-mechanically.

dubbleUJay
PS(a)-I did say that a micro-controller would be better hey! 
PS(b)-My brother IS actually working over in Ireland, no offense intended 

[BruceM]

As soon as you added one op amp, it's become a "black box" solution beyond the electronics ability of most. Even if you make a PCB, few will be able to build one.  So any solution will be a "black box".  ExpressPCB will make 3 fixed size "experimentors" boards for $53., cheap enough that I don't do as much hand wired prototypes now.

If I was the farmer, I'd rather have something that worked and was reliable. That would not include something with a DC motor driven off of a flywheel.  If you really like having such a thing, well hell, have a ball.  Just be prepared to add the op amp dampening circuit I provided.

A Picaxe chip is something developed for kids to use.  Go to http://www.rev-ed.co.uk/picaxe/   A very good book with lots of well explained basic program examples for applications is "Programming and Customizing the PICAXE Microcontroller"  by David Lincoln.

Alternately, governor performance can be improved by drilling out and re-bushing the sliding yoke piece in bronze; this seems to be where a lot of the bind in my machine was.  The stock pieces didn't support the yolk fully, were roughly finished.  The stock spring was too stiff for my machine, I found two softer springs that work better without hunting.

Bruce  

[dubbleUJay]

As soon as you added one op amp, it's become a "black box" solution beyond the electronics ability of most.   

You have a point there ....

Jens

Definitely, but more people can go out and buy a 741 op-amp than a micro that's pre-programmed with dedicated code. This can go on & on & on...........

Guys, I do get what everyone is saying and I'm not even sure if my intentions is doable!
I'll start with the mechanical side first as soon as I get a change, ie. solenoid, then, if I see the op-amp "abortion" wont work, I can always change over to a more subtle way of controlling it.

Bruce, I've gone over all the mechanical side of thing on my governor 3x and cannot find anything more that I can see that's causing it.
It does not seem to bind, because when I apply a big load, the engine droops and do not come back to the set RPM, but even if I manually then open the rack by hand a bit, it easily picks up revs, but it then still falls back when I let go 
So it seems that I'm not overloading the engine as it will "go" more and the rack is not binding as I'm overcoming that "spot" by hand and it still drops back upon release. (BTW, I'm applying pressure where the governor linkage come out of the engine, but it might be possible that I'm not "opening" the weights as such)

Now that I think of it, I've read somewhere that the weights of the governor might play a roll and I've seen photo's of the 6/1 & 8/1 weights being different.
There might be a possibility that my weights might be from the original 3/1 (if they were different), as my engine was build up of spare parts found all over.
I'll have to look into it further.

dubbleUJay

[dubbleUJay]

I know what I am trying to say ... it just doesn't come out right. Anyway, point being that the governor can keep you in a certain range but can never keep the rpm constant over the entire load range.

Jens

I get it Jens, its no wonder I cannot find anything more mechanically wrong with my whole governor assembly! Obviously you did your homework much better than I did.

So an extra "smaller" spring, released up to about half load (or wherever the frequency is still acceptable), but pulling upon full load (or wherever the frequency starts to be unacceptable), to bring the RPM up just a little bit, "should" do the trick and that is what we would like to achieve?

Somewhere in between there is going to be a point where the solenoid (op-amp) will slowly oscillate when the frequency is just about right, but due to the lag in the flywheel (actual frequency, not the frequency the "black box" is trying to achieve) this should only be a few revs either way. (And this is a big I THINK) 
Maybe something as crude as just the solenoid coming in at a 2hz drop might do the trick and be acceptable 
I don't mind a slow oscillation of between 49 & 51hz with a constant load, but my UPS's start to complain round about 46-47hz.
If only I had some current sensing or frequency sensing relay or something just to test the theory 
Anyway, I'll get there in the end!

dubbleUJay

[mobile_bob]

a couple of thoughts if i may

has anyone tried to tailor the governor linkage to allow the flyweights to run either further out
or closer in at governed speed to see how they work against the spring? sometimes a bit of tweaking
here can make a huge difference in how the governor responds to load.

the old detroits had an airgap adjustment that had to be made very precisely at a specific rpm or all
bets were off on the engine power being what it should be, or governor responce would be sluggish etc.

failing that, how about this

a second spring to work in tandem with the stock governor spring to bias it as needed.
the second spring could be attached to a solenoid that instead of being a simple on/off affair
could have the coil replaced with one of fewer and heavier wound turns with the st head output running through
it.
then as the st head started to produce more amps for a heavier load the solenoid would start to pull increasingly harder
on the bias spring and help to maintain the proper rpm

it would take a bit of finigaling (tech term) to get it right, but out to be workable to some extent i would think

bob g

[mkdutchman]

mobile_bob,
I've wondered about that solenoid tied to gen output idea too......

Wouldn't it be possible to just eliminate the mechanical linkage entirely and have the solenoid do the duty of the linkage? I suppose you would still need a spring, or would it be possible to replace it with a weight?

[mobile_bob]

MK

i suppose anything is possible, i would hate to suggest anyone try it though
seems like if you got it wrong things could get really serious really quick

at least with the oem governor in place you got a failsafe control of the engine
and i think it might be prudent to keep that in place.

thats why i like biasing against the oem governor or its spring
anything fails electrically and you still have control over the rpm

i just don't think i am good enough to take the risk myself, and surely nowhere
near good enough to suggest anyone else try it.

maybe there are others that know more than me, which i am sure is the case
perhaps they got some idea's on how this might be done,, certainly a lot of interest
it appears.

bob g

[BruceM]

It is technically appealing to me to just eliminate the mechanical governor, and directly control rack position via an RC servo. (A high end metal gear type unit.) Very little force is needed to move the rack in this manner.  The software is not too challenging, either; it's a simple one axis autopilot. (And I've written a few of those.)

But it violates my own system rule- that all my electronics allow "manual reversion"; everything operates with the electronics off.

It would also require some serious secondary safety systems.  I have this, but would also want something that would assure rack closure in case of 12VDC power failure.  So decided that a mechanical governor augmenter would be the best compromise for me.

My mechanical governor can do 57-63Hz for full load range once it's warmed up. I have two springs in parallel, one is slack at rest.  It's not great, but good enough as I have my homemade AVR on my ST3.

[mkdutchman]

MK

i suppose anything is possible, i would hate to suggest anyone try it though
seems like if you got it wrong things could get really serious really quick

at least with the oem governor in place you got a failsafe control of the engine
and i think it might be prudent to keep that in place.
bob g

that's very true, and I've never tried an electrical only speed regulation. But take a look at the mechanical governor on the 'oid or changfa. All you have is a spring pulling the rack open and engine rpm working to close it. Why does the rpm-keeping-it-closed have to be mechanical? Would it be possible to do that electrically (not electronically) with just a small solenoid directly on the rack and a voltage source tied to rpm?

Keep in mind I've never tried this, it's just an idea that popped into my head in the middle of this discussion.

[akghound]

Here we go again. I know this has been rattled around a lot already but I blew up some more light bulbs and a battery charger .... Again.
It was cold and we were running a small electric heater for the bathroom when the breaker on that circuit popped suddenly unloading the generator. Of course it over revved  and ...

Based on the earlier posts on this thread, here is what I'm thinking.
Monitor either the voltage (E) or the frequency (Hz) of the output of the generator. Program something in such a way that if the E / Hz raises or drops a servo responds to the fuel rack.
However, if E or Hz goes over or under a certain set point, the fuel rack is closed and the engine shuts down. This would be for the times when there is a fuel or engine problem or a belt breaks or slips off.
Keeping the OME governor intact as an excessive over-rev safety would be important to protect the engine.
So my question is; Where can I go to find out what to use and how to program it for this. I'm willing to put the time and investment into such an idea.
Thanks
Ken Gardner

[dubbleUJay]

Monitor either the voltage (E) or the frequency (Hz) of the output of the generator. Program something in such a way that if the E / Hz raises or drops a servo responds to the fuel rack.

So my question is; Where can I go to find out what to use and how to program it for this. I'm willing to put the time and investment into such an idea.
Thanks
Ken Gardner

Ken, stick around, I cannot promise anything, but I'm looking into it at the moment. I just want to get all my ducks in a row!

This guy from the link below has done a lot of work on the subject with an electronic controller, but its quite involved and a lot of people (most) would not be able to do it, but if you read his pages, you get the general idea.
http://martin.nile.googlepages.com/automaticgeneratorcontroller

I'm looking for something simpler (probably with less features) and readily available, that I can build up myself, otherwise one can just go out and buy one of these:
http://www.fwmurphy.co.uk/products/engine_controls/engmot_asm150.htm
but that wont be a proper DIY project! and its functions would be limited.

So I was looking into using one of the regularly available experimental project boards for programmable micro-controllers, something that a lot of folks out there are using for other things and implementing it as a standalone automatic engine controller and also a data logger to PC.
Now, that said, I'm no programmer, but if I get the right board that has a big following all over the world, I'm 1/2way there I think.
At the moment I'm looking at this board which seems to be very popular and available in most places:
http://www.arduino.cc/
Actually the USB version over here, but the 1st page explains more:
http://arduino.cc/en/Main/ArduinoBoardDuemilanove
and they seem to be very competitively priced to other products of the same nature at about $30 from Sparkfun:
http://www.sparkfun.com/commerce/product_info.php?products_id=666

Now, I'm not even sure that this board can do all the things I'm wishing for, but I'm asking around if it is capable of doing it in some of the forums and should have an answer soon, hopefully! 
For one, the various sensors will have to be interfaced with the board first and I'm not sure if a program can be written to communicate the various conditions coming from it, to display and log it to PC!

The bottom line is, this is going to be a big and long project/exercise, for me anyway, but on the other hand, if I get the right guys to help with the PC interface/program it will help a lot.

In the meantime I was looking into implementing a simpler semi-temporary device like this thread suggested that wont take so long to do.

If this thing can do data acquisition only for me, it will be worth my while. Think of all the nice graphs one can make if you have all the various temperature, voltage & amps to work out loads exec., while you are running the engine on different fuels! All in real time and logged!
We'll see what the future holds I suppose, I just have too many irons in the fire right now, 'cus this will need all my attention

dubbleUJay