Gearing up a turbine

[smcardle]

Hi All,

I have been reading the content on this site for some time and have a small interest in gearing up a turbine.

Most of the posts I have seen refer to setting a gearing ratio of X:Y which seams to be calculated based on a desired generator speed for their desired optimum power output.

This doesn't seem optimal to me as it will only deliver optimum output at a that RPM. So I was wondering whether anybody had tried using a variomatic gearbox as used in some motor scooters developed from the original DAF car design by the DAF car company in Holland many years ago?

This is a smooth continuous gearbox that produces no revving effect or sudden loads due to gear changes such as those produced when either automatic or manual cars change gear. So as the wind speed picks up or drops off the gearing changes the torque at the turbine to produce the optimal output across a wide range of wind speeds.

Steve

[Flux]

For small turbines all forms gearing are more are more trouble than they are worth. If you must use something then decent enclosed and lubricated roller chain drives are probably best. Hardened and ground helical gears probably come next.

Belts are not good and any form of variator belt drive would be a constant problem.

Not to say that it won't work but there is really no justification now that we have decent neo magnets. Before the days of neo it was usually possible to reach a cheaper solution with gearing rather than very large alternators.

Flux

[smcardle]

Thanks Flux.

One thing seems to be bothering me about your comment though.

If gearing was used when magnets were not efficient, then why not use gearing and efficient magnets? surely this would be a benefit...

Here is what I am looking at for the VAWT I would like to build.

A pancake generator about 11.5inch diameter with high grade magnets and maybe some iron core to help the Flux, probably twin rotor. As it's a VAWT it should have reasonable torque to get over any cogging or maybe just build a mostly de-cogged stator. On top of this is fitted a gear box of some description (I think I would like to try a variomatic) and on top of this is the VAWTs helical blades 18inches high and 12inch diameter.

I would also like to generate voltages above the 48volt threshold that many people here discuss and have a mini-farm arrangement consisting of 10 of them. Do you think this would work?

Steve

[Todd a]

I think belt driven is the way to go.  Yes they do wear out, but you should be able to get a good year of more out of the belt.  Belts tend to be much quieter and will cause lets drage on the system then gears.

The main purpose for gearing is if you have a generator that needs say 1000RPM to start really making power, but even without a load you TSR is keeping the RPMs of the wind turbine down at say 200RPM.  Well you would need a 5:1 ratio.  Now you need a turbine with a lot of torque to handle a 5:1 ratio.  Thins like a push based VAWT, which have a TSR of 1 or less typically have a lot of torque (do to larger serface areas) really handle the gears better.

This is generally a must if you are using a DC motor as a generator as the require 1-2,000 RPM typically... and realistically a HAWT with this type of RPM would be VERY scary and noisy.

I am planning a VAWT that is a combination of drag and lift, so I am hoping on a low wind start-up and a moderate RPM (for a VAWY at least).  I have a DIY home generator that can hopefully work at the lower RPMs, but I likely will need a pulley system more like 2:1 to 3:1.

[spinningmagnets]

Google "Peltzer electric bicycle". He used a toothed belt and he did a lot of research to find the cheapest supplier

[ghurd]

You need to find a better motor.  

Even $20 treadmill motors do better than 1000RPM for 12V.