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speed control/governor
dmottaway - 13/3/06 at 05:26 PM

have an engine gathering dust in the corner. thought I might put it to use driving a generator, put am stumped as to how to devise a governor for it.

any ideas, the locost-er, the better?

dave

Jon Ison - 13/3/06 at 05:41 PM

I would have thought summat too lock the throttle position you could set under load ?

Like a choke lever on the throttle cable maybe ?

stevec - 13/3/06 at 06:05 PM

What about something like this.


http://www.railway-technical.com/governor.gif

MikeRJ - 13/3/06 at 08:19 PM

quote:
Originally posted by Jon Ison
I would have thought summat too lock the throttle position you could set under load ?

Like a choke lever on the throttle cable maybe ?


No good for a generator, any change in load would cause the speed to change.

You might try something like the old petrol lawnmowers used, basicly a spring loaded flap that gets pushed out by air from a fan. In the old Briggs and Scrapiron, the fan was part of the flywheel/magneto, but any kind of engine driven fan could be used.

Jon Ison - 13/3/06 at 08:26 PM

depends on engine and generator output i guess.

dmottaway - 13/3/06 at 10:44 PM

thanx for the replies!

my first thought was the railway device from stevec, but couldn't figure how to drive or calibrate it, let alone make one.

I really like the wind driven flap idea - will ponder that one some more!

the notion of using a megasquirt also crossed my mind. surely it has some sort of out put that could be used to drive a stepper-motor to control the throttle. then it becomes complicated, overkill and not really in the locost philosophy.

thanx for the help.

dave

MikeRJ - 14/3/06 at 11:19 PM

If you want to go technical then I had a plan to upgrade a cheapy generator that my cousin brought to me for repair...but couldn't be arsed in the end.

I was thinking of using a servo motor (as used in radio controlled models) controlled from a PIC micro. The PIC would measure RPM from the generator output and use a digital PID control loop. You could get a very stable 50Hz output with the benefit of much better transient response than mechanical governors could ever provide.

You could build something simmilar purely in analog using a frequency to voltage converter (e.g. 555 time in monostable mode with low pass filiter, or 4046 Phase Locked Loop) with an analog PID control loop which could drive something like a solenoid actuator, as used in idle control valves etc.

[Edited on 14/3/06 by MikeRJ]