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CWAVE
Starting Member
Canada
21 Posts |
 Posted - 05/05/2008 : 15:06:34
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I have been reading about blades, and notice that some people gear up their generators.
Was thinking that perhaps I should do something like that with mine to build higher RPMs on the generator.
How is this done? How I'd envision it would be to simply mount the generator lower on the assembly, then connect the blades to a hub on shaft (supported by bearings) that is in turn connected to the generator through gearing.
The gearing method has me perplexed. Would you use :
- A belt (not my first choice as I'd see there being more resistance and prone to slippage).
- Chain Drive?
- Gear Drive?
Those are pretty much the only options that I can think of. I'd be leaning towards a chain drive arrangement myself, given the fact that I have access to a store that has all sorts of different gears on hubs in various sizes, that would allow me to get a really great ratio going. Gears would be my next choice, however, finding something that would work I'd imagine would be tough.
Once the bugs are worked out on the gearing, I would imagine that you'd go with REALLY BIG blades then. Something that would catch a lot of wind energy, given that the assemly wouldn't need to turn very fast to make the generator spin REAL fast.
What are your thoughts on this?
Thanks for your time. What an exciting hobby this is!
Thomas
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windnovice
Starting Member
USA
32 Posts |
Posted - 07/05/2008 : 03:01:40
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| I was wondering the same thing, i figured the easiest thing to do would be to use a bike chain and gears to gear it up using that. although i dont know how much force the chain can take since its a small bike chain. but i figured it would be the cheapest and easiest thing to get ahold of. |
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sacongo
Starting Member
USA
39 Posts |
Posted - 07/05/2008 : 05:53:30
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Here is a nice lay out of a geared GM alternator(welding required) I have see one bolt together but i cant find it, i be still lookin.
The Weird thing is it looks like these two sprockets are very close in size which would not be raise the rpm by much.
http://www.windstuffnow.com/main/newpage5.htm < Ben hope this link ok with you if not please remove
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Edited by - sacongo on 07/05/2008 06:01:52 |
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CWAVE
Starting Member
Canada
21 Posts |
Posted - 07/05/2008 : 05:58:14
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The thought had crossed my mind with respect to gearing as I thought about wind generation over the years. As I envisioned it, it wasn't so much a matter of trying to utilize a generator that runs best at higher RPMs than to reduce the overall rotational speed of the blades while maintaining good speed and power generation from the generator.
What originally got me thinking about so called "gearing up" was a visit to a very windy location in Alberta called "Pincher Creek" Looking at those megawatt wind generators (38 in total), they only spin at 16 RPM. Clearly there is a transmission of some sort... ie: gearing involved to bring the wind turbine rotational speed up to an optimal RPM. Obviously the transmission in that would be more sophisticated than what we're talking about here (ie: chains and gears) but the same sort of thing could be accomplished.
http://www.canwea.ca/images/uploads/File/Summerview2.pdf
My thoughts are as follows. Feel free to chime in and shoot me down if I'm off base here.
1. From what I've been reading, larger blades (ie: larger rotor diameter) captures more of the winds energy.
2. A ratio of say 4 to 1 could easily be duplicated with two gears and a chain.
The rotor would be connected to a hub and shaft on bearings. The generator would reside beneath the shaft, and correctly aligned. I was thinking of a small gear applied against the chain to maintain reasonable tension on it to ensure that there'd be no chain slap.
The chain mechanism and generator could easily be shielded from the weather.
1. Chain oiling regularly would be required.
2. Chain performance in the -20C to -50C degree range is unknown (yes it gets that cold here)
I would use a chain equivalent to a motorcycle chain and new gears (have a local outlet that I could get everything from) I believe it could be done quite nicely. How well it would work is an unknown to me.
I envision that it could potentially work very well. Gears could be changed out during testing to maintain an optimal output from the generator.
As I see it, with this scenario, you'd be able to capture more wind energy with a larger rotor and transfer that torque into spinning the generator at a much greater speed. You would also in this vision, limit the maximum speed of the rotor. From what I've been reading, the larger the rotor, the lower the maximum attainable RPM.
At this point, it seems to be a win win situation. But then I'll freely admit that I'm new to this hobby, and although I have been doing alot of reading, it's no substitute for experience.
Please feel free to comment and bring a light of experience to these comments if I'm way off base.
Any contribution is greatly appreciated.
Thanks,
Thomas |
Edited by - CWAVE on 07/05/2008 06:00:55 |
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CWAVE
Starting Member
Canada
21 Posts |
Posted - 07/05/2008 : 06:10:19
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That is a very nice build I must say. Clean and from the comments quite functional. It appears this individual is running a reasonably substantial chain.
Thanks for sharing the link. I rather enjoyed viewing it!
Thomas
quote:
Originally posted by sacongo
Here is a nice lay out of a geared GM alternator(welding required) I have see one bolt together but i cant find it, i be still lookin.
The Weird thing is it looks like these two sprockets are very close in size which would not be raise the rpm by much.
http://www.windstuffnow.com/main/newpage5.htm < Ben hope this link ok with you if not please remove
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sacongo
Starting Member
USA
39 Posts |
Posted - 07/05/2008 : 06:15:06
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Try it out with just the blades see how it goes you could alway gear it up at a later date.
It would be a hell of allot less work and you will see what power it get with both setups.
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Hefhoover
Starting Member
United Kingdom
30 Posts |
Posted - 07/05/2008 : 15:44:53
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A chain drive setup in good condition is supposed to be in the region of 98 percent efficient, but although he's done a cracking job on the welding, machining etc, the chain will soon degrade due to any lubrication being thrown or washed off. "O" ring type (sealed) chains are available, but these have greater friction losses than a standard chain. Also the taper bearings, are nicely adjustable for wear, but unfortunately these don't have any form of protective seal.
I don't mean to "pee on anyone's fire", just pointing out any weaknesses.
Hef  |
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windymiller
New Member
United Kingdom
57 Posts |
Posted - 07/05/2008 : 21:40:10
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Hi cwave
I did have a geared up turbine as one of my early projects and it did work quite well. (power wise)
It had a bicycle bottom bracket and chainwheel and drove an indiana pm motor (24v at around 400 rpm) five pvc blade setup approx 4ft 6inch dia
The ratio was 1:2 chainwheel to motor sprocket respectively.
The downside was.......if it was not set up perfectly,it would cause rotating problems.
Also after several hours use the chain links and rollers would wear and cause chain slack...which in turn caused the chain to jump off (annoyingly)
If i did it again id use a kevlar/nylon toothed belt and sprockets....
The belts dont stretch and are low maintanance,and can be covered to protect them from the elements.
Modern cars use them ,and some dont need relacement for at least 100,000 miles
Harleys use them as a final drive also.
There are losses....all depends on the set up you choose, also start up suffers (hence 5 blades) ....not as bad as people think though.
Cheers WM |
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Gearing up my Ametek 99
