It's really not a fan assembly. You'd design it to have a lot of
rotational drag, so it tends to lag behind the wheel speed. The
relative motion could drive the tiny pump. At freeway speeds, the
force would be large. Stop-and-go, it would work in inertia mode.
It would only need a little energy per day to keep a tire topped off.
The pump could be tiny.
It only needs rotational drag, which doesn't benefit from ducting.
You evidently haven't done the math.
I have to admit that this silly idea could be done, for example with
the "spinner" weight connected directly to the shaft of a very tiny
single piston compressor similar to a model airplane engine only
smaller, with reed in/out valves in the head and no side ports.
Bearing drag and the compressor shaft torque would spin the weight up
during acceleration, delivering a few strokes of compression, and
deceleration would deliver a few more in the oposite direction
(rotation direction is irrelevant to compressor). You could put all
the air in the tire and let out the excess with a relief valve set at
32 PSIG or whatever is desired.
But I don't like the idea, too cumbersome and delicate, and the
spinners would look lousy on my Yugo. Plus the extra unsprung weight
would spoil its handling.
What is wrong with the usual approach of instaling a compressed air
rotary joint on each axle, connected to the tire through a Schrader
valve in the wheel (so it holds air when removed). The stationary end
of each rotary joint connects to a pressure transducer and fill (from
engine driven compressor) and vent solenoid valves, controlled by the
tire inflation computer. A dashboard control lets the driver adjust
tire inflation from inside, so for instance pressure could be dropped
to 20 PSIG for driving on sand and back to 32 for highway driving, or
upped a bit for driving in rain. This arrangement works pretty well
on my Yugo
.
Glen
