Half a croissant, on a plate, with a sign in front of it saying '50c'
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Ring Spinner CVT

A strange epicyclic continuously variable hybrid gearbox
  [vote for,

(See attached image).
This is a partially self-regulating, but electrically-controllable epicyclic (planetary) transmission. I originally envisioned it for in a car or truck with an internal combustion engine (piston or turbine) as the main drive, but it would probably work with a hybrid or electric main drive as well, or in a wind turbine, or as a mechanical 'soft-start' device.
The concept is this: initially, the ring gear is stationary, providing a low gear ratio from input (sun gear shaft) to output (spider shaft). But the ring gear is not fixed; friction begins to rotate it as well (against its own inertia), effectively increasing the gear ratio up to 1:1.
But wait, there's more! Around the ring gear is a motor/generator, enabling either regenerative braking, to slow down (or allow slower speed-up of) the ring gear; or to act as a motor, to provide even higher gearing as an 'overdrive'. It would probably need a caliper brake or something to provide a 'locked' position for the ring gear.
As the 'normal' maximum ratio is 1:1, a pre- or post- gearbox is probably required, depending on the main drive speed and final use.
Much calculation and experimentation would be required in regards to actual gear ratios, masses, etc - that's the halfbaked bit.
The ShadowBuilt RingSpinner - for a smooth transmission.
neutrinos_shadow, Dec 15 2011

Ring Spinner Diagram http://s1199.photob...ent=RingSpinner.jpg
Colour-coded for your enjoyment! [neutrinos_shadow, Dec 15 2011]

How the Prius transmission works http://www.howstuff...com/hybrid-car7.htm
[scad mientist, Dec 16 2011]

bike hub with two motors
shameless self promotion [xaviergisz, Dec 16 2011]


       1) If the ring gear is not fixed, and there is a load on the spider, won't the ring rotate backwards, allowing the assembly to idle?   

       2) Using a planetary transmission to combine inputs and outputs (such as engine - motor/generator - drive shaft) like this is well baked.
spidermother, Dec 15 2011

       Congratulations, you just invented the transmision in the Toyota Prius. Well, you left out a few bits and connected the inputs, output and motor/generator to different points of the planetary gear, but I'm confident that if you did enough calculation and experimentation you'd end up with about the same solution. See link for a nice description of how the Prius works.
scad mientist, Dec 16 2011

       I knew that, but felt it was like mentioning the Space Shuttle to demonstrate that aerodynamic lift has been invented.
spidermother, Dec 16 2011

       I must confess, I didn't do much digging before posting this.
The electric motor around the ring was an after-thoought, more for energy efficiency (power back to a battery, rather than lost as heat) than as a drive.
The caliper brake could be applied at start-up if required.
I would say that 'bits missing' and the arrangement of input and output were rather important in a design. Simplicity was the driving force here.
neutrinos_shadow, Dec 21 2011

       It's the old problem that, because millions of person-years* have been devoted to mechanical musing and tinkering, you are very unlikely to come up with a new and improved permutation of cogs and engines and what not.   

       If you could think of a way to use planetary gears to match the speeds of a flywheel and powered wheels, I'd be interested; but see above.   

       *Figure made up on the spot.
spidermother, Dec 21 2011


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