Pitch control part Duex

[Murlin]

Howdy Folks.

I have switched sides of the fence on this issue more than your average politician, but have come up with a downwind turbine design that uses a servo for pitch movement.  The design is sound but has the downside of incorporating electronics.

The design I had finally settled on, incorporats a single attach point and had a hollow axle.  The turbine does not furl and the wind controls the yaw.

Then I had a wild idea of pitching the blades manually or with a ground based hydrolic system. The hydrolic system would use no electric motors. It would use a large anonometer to drive the hydrolic pump and would rotate on the bottom section of the tower. Springs on the rotor side and a counter weight on the cable would balance out the load needed to adjust the blades.

On the manual version, a steel cable would traverse up the center of the tower and a bellcrank would pull/push the pitch rod going through the axle and adjust the pitch of the rotor blades.

On the ground, you could have a set lever with a spring loaded pin realease to adjust the rotor blades to any pitch needed manually.

If automation is desired....A hydrolic cylinder could be used on the ground to pull the cable and automaticly adjust the pitch.

The faster the anonometer turned, the more pressure would be put on the cylinder and the the pitch would be adjusted by windspeed and totally adjustable.

Anyways just some Ideas I have.

Thought I would tell you guys about the abstract and try to get some input.

Thanks for your time.

Murlin

[maker of toys]

why not just put the pump on the the main turbine, and save a bunch of plumbing? you could do this by simple expedient of extending the shaft and attaching it to the pump (via LoveJoy coupling?) after it passed through the alternator. Or, to be a bit kludgier, a cog-belt off one of the rotors?  

you could probably manage the whole thing with the power-steering apparatus off a car or truck. (late model ford rangers even have a cute little heat exchanger in the system, not that you'd need one at ca. 200 rpm, unless things were REALLY gusty)

a little creative cutting on the steering box will yield up the servo-valve that controls which way and how much the system tries to boost the steering; the altenate application should be apparent. you could get the pitch command signal from a fly-ball setup rotating with the turbine shaft, or maybe a drag-vane. . . the drag vane having the advantage of being easy to over-ride with a cable or pushrod arrangement from the ground.

add a light spring (or a pulley/wieght arrangement) to push things to fine pitch in still air, and a double-acting hydraulic cylinder, and you're set.

the iron-mongery is left as an exercise for the reader.  <G>

-Dan

[scottsAI]

Hello Murlin,

Last April I started out with a goal to design a 10kw wind turbine.

Design started out exactly like the 17 footer on otherpower.com except 24'.

During the course of the summer I read about 3 fried stators, all were the larger wind turbines. This caused me to revisit the design.

Furling system problems, several systems had tails bashing into the blades.

A discussion with Sampower offered up a eureka moment for the final detail I didn't understand, started working on a wind turbine simulator. For a given blade, wind, battery etc can predict charging current. Fun stuff. Side tracked now, working on the FIRST robot competition for the next 4 months.

In summery

Active pitch control required. Wind turbine will be destroyed by wind gusting without furling or active pitch control. I do not like furling. For me, a brushless 3ph motor on the hub to control pitch, powered by a very small 20watt PMA generator. Controllers goal will be to max RPM within a window. Sort of like MPPT for solar.

PMA or induction motor generator? For $300 I can buy a 15ph 3 phase induction motor, use as generator. How much will a PMA cost to produce 15hp, How big, etc. The large wind turbines are induction generators (motors), so why not do the same thing? One down side is speed up gears are needed, so will use parts from rear end, and transmission from a vehicle. Plan to put the generator on the tower, No cable to deal with, wireless control for shutdown on the pitch controller.

Induction motor requires near constant speed, good thing already on board with active pitch control!

I could go on, if interested, drop me a line or check my back posts (might take a while!-)

Have fun,

Scott.

[Murlin]

Hi Scott, 'bout in the same boat as you are.

I have 2 more years and I need to get this project done.

I have one solution to active pitch control worked out.  Will work on all Jennys.

Had to do a total redesign on the Jenny though.

Open loop for PMA Jennys....closed loop for constant speed pitch control systems.

I discarded the trailer hub assembly and I am making a hub assembly from scratch since the only off the shelf items are the bearings.  The rotors I have already made will work great.

My plan was making the open loop PMA version that is an off grid/ stand alone system.

However, I will be looking very closely at my new idea of on the ground hydraulic pitch control. It is extremly simple

It has a promise of better reliability with the less maintanence and is 100%mechanical except for of courrse the coils in the PMA part.

The only thing you would have to do is make seasonal adjustments to the cable tension and adjust for thermal expansion.

I need to kick that idea around some more and see what falls from the tree if anything.

I may end up and go that route.....we will see....any route I take requires me to build the initial device, so I now have something to start manufacturing.  Glad to be past my design impass....

OH BTW, I came up with a neat way to cut wood rotor blades in one pass with a gang saw on an arbor.  It will cut the flat on one side and change the blade and it will cut the airfoil shape on the other side.  Can be adjusted to cut any taper and pitch....even twist.  Every blade will be the same size.........fun, fun...

Murlin

[Murlin]

Shaking the tree produced this......

Interesting....

You would have to extend the attach boom to so the "energy collector paddle" on the front, would clear the top guy wires as it rotated.

This might actually work with a push/pull pitch assembly.

Murlin

[Murlin]

One could still put the paddle on the ground and have the cable running up through the center of the pole.

By doing this, you would have a 100% sure fire way of manually pitching the blades because of no furl and no brakes.

Just more crazy Ideas....

Murlin