What kind of technology would be appropriate for this application? I will list the ideas of this post according to design philosophy.
Make Slight Modifications on Proven Technology
With this design philosophy, I notice that the water pumping windmill is more than proven – it has a track record of over a century! What are it’s shortcomings? How would it be better suited for the developing world? I think lower the expense and amount of materials it requires. The old waterpumper also has low aerodynamic efficiency, so we might be tempted to attack this problem as well. But “low aerodynamic efficiency” is basically just another way of saying that it’s too expensive, since people usually make up for this low efficiency by purchasing a larger, more expensive windmill.
So the first change I’d like to make concerns the terrible performance of its single-speed transmission. One reason for needing a large, expensive windmill is that its single speed transmission delivers such poor performance. If you have a deep well, you need a lot of startup torque to move any water, which means a large windmill. But this is so easy to fix! Today I realized how easily I assume that since the old fashioned water pumper is a simple and elegant mechanical device, then any improvements I make should also fall into the simple and elegant mechanical device category. Stupid!! There’s no reason we can’t mix modern high technology with proven old technology.
So we provide the windmill with a CVT (continuously variable transmission). There’s no need to invent one, as there are many that are already on the market. The way to develop successful engineering designs of new or re-engineered products is to assemble your product from components that are already on the market, that have a track record of good performance, and that have at least several suppliers (so you won’t have to shut down if one of your suppliers goes out of business). The re-engineered Third World Water Pumping Windmill is not an invention – it is an engineering project to make incremental improvements to the old fashioned water pumping windmill technology. It’s mostly just research, and it isn’t that hard to do.
For example, one of the decisions that need to be made is whether or not to use electricity. The windmill itself is capable of generating a small amount of electricity whenever the wind blows (which is the only time it needs the electricity!). Think of the little generators that are rotated by the wheel of a bicycle in order to light the bicycle headlight. If we decide to use electricity, then we might want to look into devices such as the magnetic clutch. The moving parts in these devices do not make physical contact, and thus have long life and require little or no maintenance. There’s another big advantage of using electricity – it allows us to use a microcomputer to control the transmission! That’s a big advantage, since the microcomputer can make accurate calculations and help us to achieve the highest possible efficiency.
If we decide to stick with a completely mechanical design, there are still many CVTs to choose from. For example, we could use centrifugal flyweights to actuate a belt-driven CVT. I’ve pasted an animation from howstuffworks dot com that shows how a Belt Driven CVT works. All we have to do is add the centrifugally actuated flyweights. (I realize we might have to violate our design philosophy here, as the centrifugal actuation system is probably not already available on the market. For this reason, we might not choose the belt driven CVT option, but if we do choose it, I think the modification is a relatively small one, and so we could probably get away with it.)
There are many options for mechanical and electrical CVTs. So we just need to do the research and development to assemble a system from these well-known technologies.
That’s all for now… I’ll update this post later with more ideas.