Author Topic: ENGINE SPEED GOVERNORS  (Read 3116 times)

Offline Brian Rupnow

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ENGINE SPEED GOVERNORS
« on: April 27, 2019, 09:04:07 PM »
Lets talk about engine speed governors. I am well acquainted with flyball governors and flywheel mounted governors to control the lockout rod on hit and miss engines. I have built many of them with varying degrees of success. Having just completed my sideshaft horizontal engine, I am interested in putting a governor on it, similar to the governor envisioned by Edgar Westbury who originally designed a governor as an "add on" to the Centaur engine. This governor fits onto an extension of the sideshaft and movement of the governor weights control how much the carburetor throttle-plate is opened or closed, by a linkage between the governor and the throttle on the carburetor. It is a centrifugal governor, controlled by the speed of the engine. Let us assume that I want the engine to run at an idle speed when under no load, but as the load increases, the engine will open it's throttle proportionally to compensate for any load which makes the engine want to stall. In order to do this, the governor weights would have to be at the full extent of their travel, outwards away from the center shaft when the engine is running at idle speed. As load from a driven device caused the engine to slow down, the weights would begin to move closer to the shaft because of spring tension and a lessening of centrifugal force. This in turn would move the lever, causing the throttle to open more and increase the engine speed to offset the slowing caused by the load.----SO--My question is, where would those governor weights lie in relation to the central shaft when the engine was shut off. Would they lie close to the central shaft causing the carburetor throttle to be "wide open", but with very weak springs so that they fly out quickly to their full extent and close the throttle plate to "idle" condition as soon as the engine goes from zero rpm to idling speed? I can't really see it working any other way. Does this mean that when I start the engine I am always going to be starting it with the throttle plate in the "wide open" position, and as soon as it starts the governor closes the throttle to "idle" speed?

Offline Rustkolector

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Re: ENGINE SPEED GOVERNORS
« Reply #1 on: April 28, 2019, 04:20:41 AM »
Brian,
With a constant speed mechanical governor the governor spring tension is fixed. When the engine is shut off the governor spring wins the tub of war and the throttle gets pulled to wide open. This is the way most all mechanical governors work on generator sets or other constant speed engine applications. The stiff springs are quick acting so overspeed is not a problem. With a variable speed governor you can vary the tension on the governor spring thereby allowing the engine to start and stop at, or near idle speed. The trade off between fixed and variable speed mechanical governors is in speed regulation. Fixed speed mechanical governors will give 3-5% spreed regulation no load to full load. Variable speed mechanical governors will normally do about 10% speed regulation at best, which is generally fine for most variable speed engine applications. With their softer springs using levers for mechanical advantage against the fly weights they are more complicated when reasonably good regulation is needed . With a slow speed model engine such as your side shaft a simple fixed speed governor is preferred, however a wide open throttle will definitely aggravate starting without a physical override at starting to close the throttle a bit. 
Jeff

Offline Brian Rupnow

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Re: ENGINE SPEED GOVERNORS
« Reply #2 on: April 28, 2019, 06:18:16 PM »
I modelled the governor based on Edgar Westbury's drawing, and it doesn't look that bad.



Offline Brian Rupnow

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Re: ENGINE SPEED GOVERNORS
« Reply #3 on: April 28, 2019, 09:14:43 PM »

Offline Brian Rupnow

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Re: ENGINE SPEED GOVERNORS
« Reply #4 on: April 29, 2019, 01:23:46 PM »
My original idea was to build this governor and add it to the sideshaft horizontal engine. The sideshaft engine runs so well as it currently sets that I have decide not to change anything on it. I may however build the governor as a "stand alone" unit and drive it with a coupling on the end of the horizontal sideshaft camshaft.

Offline Brian Rupnow

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Re: ENGINE SPEED GOVERNORS
« Reply #5 on: April 29, 2019, 03:15:22 PM »
Just as I thought, this governor lends itself very well to being a stand alone unit. This is something that could be attached to the end of my engine baseplate and coupled to the end of my camshaft. Having it's own ball bearing in the support brackets would take all the loading away from my engine cam bushings.

Offline Brian Rupnow

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Re: ENGINE SPEED GOVERNORS
« Reply #6 on: April 29, 2019, 03:30:34 PM »

Offline Brian Rupnow

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Re: ENGINE SPEED GOVERNORS
« Reply #7 on: April 29, 2019, 08:51:57 PM »
Knowing my limitations as a machinist, I decided to make the flyweights from two pieces.


Offline Brian Rupnow

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Re: ENGINE SPEED GOVERNORS
« Reply #8 on: April 29, 2019, 09:48:41 PM »


Offline Brian Rupnow

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Re: ENGINE SPEED GOVERNORS
« Reply #9 on: April 30, 2019, 12:24:33 AM »
A very pucker-worthy job so far. I started out earlier today with a crusty old chunk of 3" diameter shaft. So far--So good.

Offline Brian Rupnow

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Re: ENGINE SPEED GOVERNORS
« Reply #10 on: April 30, 2019, 03:28:06 PM »
Somebody said they were confused because they didn't see any springs on the flyweights. Here they are. I just want you to know that springs are one of those things that I find absolute S.O.B. to model. I can do it, but it takes me a long time, and since I only do it about every three years, I never remember quite how to do it.

Offline Brian Rupnow

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Re: ENGINE SPEED GOVERNORS
« Reply #11 on: April 30, 2019, 05:39:05 PM »
We got PARTS!!! These two flyweights came out very nice. Not really the weight of a fly though. More like maybe a full size rat. I have to go rake leaves for a while now before wife shoots me. Might get a start on the parts which bolt to these later today. There is a heavy rain warning for Barrie and surrounding area for tomorrow, so tomorrow will definitely be a work in the shop day.

Offline Brian Rupnow

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Re: ENGINE SPEED GOVERNORS
« Reply #12 on: April 30, 2019, 06:13:27 PM »
Jeez, what an old pussy I am!!! Raked leaves for half an hour and I have a blister the size of a dime at the base of my thumb. Rake handle wound. First layer of skin is gone. Second layer is red as  an apple. Work related injury. Guess what my son. I have your weekend all planed out for you!!!

Offline crueby

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Re: ENGINE SPEED GOVERNORS
« Reply #13 on: April 30, 2019, 06:20:33 PM »
Jeez, what an old pussy I am!!! Raked leaves for half an hour and I have a blister the size of a dime at the base of my thumb. Rake handle wound. First layer of skin is gone. Second layer is red as  an apple. Work related injury. Guess what my son. I have your weekend all planed out for you!!!
Rake? Rake? Considering how many IC engines you have made, I am surprised you have not made a leaf blower!   :stickpoke:

Offline Brian Rupnow

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Re: ENGINE SPEED GOVERNORS
« Reply #14 on: April 30, 2019, 11:49:04 PM »
Today I made the second part of the flyweights. They don't look like a lot, but it's taken a good share of my day.