Author Topic: variable pitch hub sketch (Read 13000 times)

kajs · « **on:** March 11, 2011, 11:05:57 AM »

Hi,
the idea is from patents 1482690 and 2052454. only the pitch synch/interlock solution is mine.
has anybody made a hub similar to this? maybe some pictures? does it seem like a valid solution for my big D=5m blades?
thank you very much
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1482690: http://www.google.com/patents/about?id=cQ9AAAAAEBAJ&dq=1482690
2052454: http://www.google.com/patents/about?id=CZlaAAAAEBAJ&dq=2052454

Flux · « **Reply #1 on:** March 11, 2011, 01:14:31 PM »

It seems complicated compared to the Jacobs blade pitch hub but it should work if you can solve all the usual problems of freedom to turn and slide with a fairly massive blade loading trying to lock it.

Most of the pitch control devices are simple in concept but solving the mechanical issues is a challenge. I have seen this idea proposed before but never seen it done in real life. I anticipate that the pin in the slot will prove to be a real challenge to make reliable long term.

Blade weight control looks attractive and certainly Jacobs managed it but I am not sure how much experiment it needed to get it right. I found that with the governor type pitch hub everything depended on absolute freedom of movement and that is much easier to manage when you only have rotation to consider, once you add sliding then things start to get complex.

Flux

kajs · « **Reply #2 on:** March 11, 2011, 02:31:05 PM »

@Flux
thank you, sounds reasonable. then i will wait till i go to city and check if i can get some gears for a non-sliding solution.

Harold in CR · « **Reply #3 on:** March 11, 2011, 03:18:50 PM »

There are no gears needed in the spring controlled Jacobs type centrifugal governor. It is as simple and strong as anyone can come up with.

kajs · « **Reply #4 on:** March 11, 2011, 03:32:14 PM »

@Harold in CR,
do you mean this?:
http://www.greenpowertalk.org/attachment.php?attachmentid=722&d=1259093155
i have to go downwind.

Flux · « **Reply #5 on:** March 11, 2011, 03:43:12 PM »

I don't see why the Jacobs unit won't work down wind as long as you mount the blades the other way round. I haven't thought it through fully but you may have to fit the spider links to the other side or use reverse aerofoil blades.

Normally downwind machines use some form of coning to reduce blade stress and the Proven machines incorporate coning and blade pitch. Somehow they seem to get away without blade synchronising.

Flux

kajs · « **Reply #6 on:** March 11, 2011, 04:29:54 PM »

oh, i thought that machine was working similar to a previous jacobs invention, where there was a second axis for blades. hmm. i'll think about it, though it seems without lathe it will be difficult if possible.

Harold in CR · « **Reply #7 on:** March 11, 2011, 05:43:56 PM »

YUP. That's what I built, only with 1 spring per blade.

The center that you hook the springs in to, looks like a washer with a ring welded around the edge. A place is left open at each 120Â° spacing for the spring to hook. The washer slips over the end of the center shaft.

Just take the whole set up, and mount it on the tail end of the generator. NO need to turn anything around or reverse anything. Just make sure it spins the shaft in the correct rotation.

I'm using a sawn off section of 5" solid bar for the hub. Bought a Â¾" weldable coupling, and drilled out the center on a milling machine. I need to true it, and then, turn down the coupling to press fit into the hub. That allows a reduced sized hub on the back side to put the 3 legged spider on. That part should have a Brass sleeve pressed in, so it will take the slipping of the spider on the hub. That spider slides in and out on the hub as it twists a bit. That's what causes the blades to twist as they speed up.

It's just plain stupid simple. Get 3 "Heim Joints" to attach to the ends of the hub shafts and to the angle on the blades. The blades are bored to allow the shafts to fit up in to the base of the blades. I used EMT Conduit and welded it to the angles. Bolt the angles on the blades. It takes some careful measuring but works like a charm.

Bolt angle pieces up on the blades and measure so the springs need tension to hold the blades at low speed.

Just need to experiment with springs and tension. On my 4KW machine, I used "Field Tiller" springs and cut off 2 coils and the hook end and reformed the ends of the coils From where I cut the ends off. Used eye bolts for the adjustments with lock nuts.

Oops, forgot. Do some more Google for Jacobs centrifugal governor, and you will find photos of the back side of the hub with the spider. . Good luck.

kajs · « **Reply #8 on:** March 11, 2011, 05:50:19 PM »

thank you.

cdog · « **Reply #9 on:** March 14, 2011, 11:45:03 AM »

http://tinyurl.com/5vc3jbr (ttp://www.builditsolar.com/Projects/Wind/TomTurbine/Jacobs3.jpg)

Why not like this with three pinion gears and a ring gear?

Your first link had a length of 659 characters. Please use a redirect service like www.tinyurl.com. dang

kevbo · « **Reply #10 on:** March 16, 2011, 11:35:49 AM »

Half of that mechanism is redundant. You only need one of the three legged spiders and three links to keep the blades synchronized. That almost gets you to the Jacobs mechanism, the Jake uses the links operating on levers to also do the pitch control so the cam slot and pin are not needed. I can't tell in the drawing how the links accommodate the pitch rotation of the blades. Assuming it is some sort of ball joint, then you have all the elements of the Jacobs mechanism plus the added complication of the cam slot and drive pin.

kajs · « **Reply #11 on:** March 16, 2011, 02:52:13 PM »

Thank you for your input, i will try the Jacobs type. let's rip this post, i do not want to fluctuate with the decision.

cdog · « **Reply #12 on:** March 16, 2011, 05:42:04 PM »

I thought the pic I displayed was also a jocobs design?

SparWeb · « **Reply #13 on:** March 16, 2011, 05:58:38 PM »

It sure looks like the spring resists almost 100% of the radial force on the blade. The mechanical advantage the blade has over the star is very large.
The angled slot probably does the blade retaining load, instead of the spring, but the friction of the pin against that slot much be tremendous.

These sorts of things usually make more sense to me when I can see them built - not as sketches like that.

kevbo · « **Reply #14 on:** March 17, 2011, 06:02:11 PM »

Quote from: cdog on March 16, 2011, 05:42:04 PM

I thought the pic I displayed was also a jocobs design?

It is, but there is a gear less design made by the "new" jacobs company. Yours is the old style dates back to the 1930s. The newer type uses the mass of the blades instead of separate fly balls, and a 3 point synchronizing "star" that cranks the blades via ball joints. The Jacobs star slides forward and aft on the shaft, and rotates to change the pitch.

ChrisOlson · « **Reply #15 on:** March 17, 2011, 07:10:07 PM »

Quote from: kevbo on March 17, 2011, 06:02:11 PM

and a 3 point synchronizing "star" that cranks the blades via ball joints. The Jacobs star slides forward and aft on the shaft, and rotates to change the pitch.

That "star" is called the spider and it connects to the blade brackets and slides on the rear of the governor hub on a nylon sleeve. This is an upgraded 1-3/4" governor for a 23-10 Jake. The original had 1-1/4" blade shafts and they were notoriously weak. Mine flexed and hit the tower and blew all the blades off it. The blade brackets slide over the blade shafts, then the blades slide over the brackets and are bolted to the brackets with four bolts.

The governor springs are adjusted by measuring the length, hook to hook, from the spring spider to the eyebolt.

cdog · « **Reply #16 on:** March 17, 2011, 10:01:33 PM »

Thanks for the clarification, were there any shortcomings with the older gear style, if I were to home build, what style would be better?

ChrisOlson · « **Reply #17 on:** March 17, 2011, 10:18:14 PM »

Quote from: cdog on March 17, 2011, 10:01:33 PM

Thanks for the clarification, were there any shortcomings with the older gear style, if I were to home build, what style would be better?

The new style Jacobs governor is better. The gear units were high-maintenance governors.

There's been the fair share of problems with the later governors too, but mostly on the 1-1/4" units - broken blade brackets and a lot of tower strikes. When Wind Turbine Industries Corp bought the manufacturing rights to the Jacobs turbines in 1986 they switched to glass blades. The 1-3/4" governor with glass blades is just about bullet proof.
--
Chris

cdog · « **Reply #18 on:** March 17, 2011, 10:36:10 PM »

Thanks again, I think the newer way is very clever, but I cant get the old style out of my head, surely it could be beefed up and reliable?
What were the flaws?

ChrisOlson · « **Reply #19 on:** March 17, 2011, 11:29:59 PM »

Quote from: cdog on March 17, 2011, 10:36:10 PM

Thanks again, I think the newer way is very clever, but I cant get the old style out of my head, surely it could be beefed up and reliable?
What were the flaws?

I suppose it could. You could ask Tom Sullivan because I think he restored an old Jacobs Model 18 with the gear governor on it with the flyweights. The gear governor had a lot more moving parts with the flyweights pulling against tapered springs and when the flyweights moved out they had arms that turned a brass spider, which turned brass gears retained to the blade shafts with a square head set screw and key.

And then IIRC, there was springs on the blade shafts that pushed on the back side of the brass gears and kept them in engagement with the brass spider. It was a horribly complicated affair compared to the new style governor.
--
Chris

kevbo · « **Reply #20 on:** March 18, 2011, 11:40:30 AM »

To be fair, the flyball & gear governor did work, and the fact that folks are putting them back into operation means at least some of them lasted. In interviews I have read, Jacobs liked to brag about the letter he got praising his machines performance and durability in Antarctica.

It would have been pretty hard to make the new type work back in the 1930-40s. The whole mechanism is exposed to the elements. It depends heavily on self-lubricating plastic bushings that don't rust and allow low friction without the grease that would end up full of dirt and grit. Also it might be pretty hard to enclose the springs, and there were no durable polymer coatings back then to keep the high-carbon steel springs from rusting. Today you can find catalogs filled with the ball and socket joints that are the key to it's operation, back then these would have been exotic pieces.

Jacobs was trying to keep things enclosed so the grease he had to have to cut friction and prevent rust would stay clean. The one thing I wonder about is why he didn't take the motion of the flyweights into the case via shafts instead of having to have those openings for the crank arms? This would have allowed a much tighter case. Probably had a good reason....money was very tight back then, so the way it was done was probably a compromise toward fewer parts, less machining, and lower cost. It does look like he was trying to keep the weights and the blades on the same plane though. Those notches in the crown gear could have been avoided if the weights had driven pins on the front of the gear instead of fighting with the pinions for space on the back. Might be a reason for that I'm not seeing.

ChrisOlson · « **Reply #21 on:** March 18, 2011, 12:13:55 PM »

Quote from: kevbo on March 18, 2011, 11:40:30 AM

To be fair, the flyball & gear governor did work

I suspect that what you're saying is probably true about the available materials and machining processes at the time being the deciding factor in that flyweight governor that Joe Jacobs invented. Marcellus Jacobs came up with the later one and I think it was an evolution of the fact that I've heard old Jake men talk about those flyweight governors allowing the blade pitch "out of time" as they wore.

But even the later governor had a lot of teething pain. There was a lot of Jacobs turbines installed in Alaska in the 80's that had the lightweight 1-1/4" governor with spruce blades, and very few of those turbines made it thru their first winter and still had blades on them. They were simply too light duty for the conditions there. WTIC ended up replacing those with the new bigger governor and fiberglass blades, and then they lasted. But then the inverters wouldn't take it and they blew inverters one right after the other. A lot of those old Jake turbines are still standing there in Alaska not being run because the inverter is blown and they finally gave up on them.

The company that put those Jakes in in Alaska (It think it was Four-Winds of Alaska) finally went out of business. A lot of the villages and towns where those old inoperative 10 kW Jakes are are now getting new Northwind 100 turbines that are designed specifically for the arctic environment.
--
Chris

cdog · « **Reply #22 on:** March 18, 2011, 04:13:02 PM »

I was daydreaming of a flyweight govenor completely encased and full of gear oil, any opinions here?

Flux · « **Reply #23 on:** March 18, 2011, 04:55:07 PM »

There is absolutely no reason why a flyball governor can't be enclosed in oil and be totally reliable.

There is also no doubt that it would be expensive to produce, how much this matters I don't know. The Jacobs design was no doubt very restricted by costs and it looks very much in the style to all the agricultural mechanisms of the time open construction, cast gears and restricted machining kept the cost within limits. it worked as long as you maintained it. At that time there would have been problems with seals and stainless shafts and all the other things needed to make it to aircraft standards and the cost would have prevented worthwhile sales.

Various other manufacturers have made good flyball type governors including Elektro, Vergnett,Dunlite, Aerowatt and others. All have been at the expensive end of the range. I see no reason why the Chinese can't produce these things very cheaply but perhaps they can make good enough machines without.

If the market will stand the cost there is no problem, but in the end it has to sell in sufficient quantities to be a commercial success, The Jacobs was an expensive machine, they only held the market because they were long lived and reliable.

Flux

cdog · « **Reply #24 on:** March 18, 2011, 05:11:26 PM »

Thanks, I really would like to build an encased one, I cant see it being that difficult.

ChrisOlson · « **Reply #25 on:** March 18, 2011, 08:23:57 PM »

Quote from: cdog on March 18, 2011, 05:11:26 PM

Thanks, I really would like to build an encased one, I cant see it being that difficult.

Do like I do. Just build it and see if it works. Post some pictures so people can see how it's done. If it don't work, post pictures of the explosion. People like those too.

--
Chris

cdog · « **Reply #26 on:** March 18, 2011, 09:32:17 PM »

Youre a sick man, I love it!

cdog · « **Reply #27 on:** March 18, 2011, 09:33:40 PM »

I was thinking 3 pinion gears and a ring gear, surely they would be far more robust than the brass teeth on the jocobs.....

ChrisOlson · « **Reply #28 on:** March 18, 2011, 09:43:43 PM »

Quote from: cdog on March 18, 2011, 09:33:40 PM

I was thinking 3 pinion gears and a ring gear, surely they would be far more robust than the brass teeth on the jocobs.....

Just cob some differential gears out of a truck rear end. Use one of the side gears for the crown gear and the pinions for the blade shafts.

You better get going on this right away or I'll get all worked up over it and build it for ya'.
--
Chris

cdog · « **Reply #29 on:** March 18, 2011, 09:50:26 PM »

I was also thinking using the pinion bearing to support the end load, using 2'' chrome hyd cylinder shafts, a hyd seal from a piston in the shaft that supports the 2'' and also inserting a cast iron sleve for the chrome shaft to ride in?

phil b · « **Reply #30 on:** March 19, 2011, 09:52:59 AM »

I just ran across this site. It may be of interest.
http://www.jacobswind.net/marcellus-jacobs-at-the-state-fair-1981

Marcellus Jacobs at the State Fair
Posted on January 19, 2011 by Steve Jacobs

ChrisOlson · « **Reply #31 on:** March 19, 2011, 05:00:32 PM »

Quote from: phil b on March 19, 2011, 09:52:59 AM

I just ran across this site. It may be of interest.
http://www.jacobswind.net/marcellus-jacobs-at-the-state-fair-1981

That's actually Paul's website - Paul Jacobs lives in Corcoran, Minnesota. If the history of Jacobs wind turbines is of interest click on the history link on the website. I always chuckled over this one:

On July 15, 1985 M.L. Jacobs died as a result of injuries suffered in an automobile accident. At the age of 82 he had played an integral part in the beginning and rise of wind energy, and moved it along even further during its second big wave. Marcellus, outspoken and honest with his opinions, brought both admiration and scorn during his lifetime. His story inspired those entering the industry, while his blunt language rubbed some the wrong way. Some engineers especially did not appreciate being told they didn't know what they were doing by a man who held no formal degree. The reputation of his machine spoke for itself and Marcellus was not shy in saying so.

LOL! You got your book-learned engineers with lots of theories and formulas and then you got real engineers that build machines that work. The two are rarely the same.
--
Chris

Dave B · « **Reply #32 on:** March 20, 2011, 03:06:49 AM »

Perfect Chris, nothing more to say about that quote. Dave B.

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Author Topic: variable pitch hub sketch (Read 13000 times)