Hi MIKE.

02-Sep-03 21:36:20, MIKE ROSS wrote to WAYNE CHIRNSIDE


 MR> "WAYNE CHIRNSIDE" bravely wrote to "MIKE ROSS" (01 Sep 03
 MR> 21:14:00) --- on the heady topic of "Re: Vehicle LED's"

 WC>> When I was a kid my bicycle had a generator that was part of the
 WC>> hub. Back in 1967 a 3 speed with this arrangement cost somewhere
 WC>> around 100 dollars. Far better than those little things that rub
 WC>> the tire.

 MR> How was the power taken out, insulated slip ring?
possiblt a terminal on the end of the axle

 MR> I'm guessing it required a lot of poles to generate any kind of power?

or some steep gearing.

were I asked to design one I'd do something like this

    ******************************         *****  hub
    *                   H    H   *         *****
    *   -------------.  H    H   *
    *   -------------|  H |  H   *         #####  wheel axle
    *   -------------| -H-| -H-# *         #####  and flange
    *                |  H |  H # *
    *   WWWWWWWWWWWW |  H |  H # *          H    gear
    *   WWWWWWWWWWWW |  H |  H # *         -H-  gear axle
    =   WWWWWWWWWWWW `--- `--- # =
 ####################################      ||||   rotor
    =   WWWWWWWWWWWW .--- .--- # =         ----
    *   WWWWWWWWWWWW |  H |  H # *
    *   WWWWWWWWWWWW |  H |  H # *         WWWW  stator attached to
    *                |  H |  H # *               wheel axle
    *   -------------| -H-| -H-# *
    *   -------------|  H    H   *
    *   -------------'  H    H   *
    *                   H    H   *
    ******************************

the two sets of planetary gears should give a pretty serious
ratio getting about 6:1 on each one should be easy, as a result
a 36:1 gear ratio would be obtained

and if you use more poles in the rotor/stator a further improvement could
be had.

the MR> rotational speed of a bicycle wheel is much slower than its radial
MR> velocity, it must have been dim at slow speed, no?

 MR> Consider that 1mph is about 1.5ft/sec and a wheel periphery
 MR> measures about 7 ft, then 1 revolution/sec = 4.75mph, so 20mph is
 MR> only about 4.2 rps or 252 rpm. A 60 hz generator needs turn at
 MR> 3600rpm! Luckily with the rim generator, the gear ratio is about
 MR> 35:1 so in priciple at 20mph it is generating at about 150Hz.

 MR> At 252 rpm the hub generator would require the equivalent of the
 MR> gear or 35 poles. OTOH maybe there was a gearing system inside?
 MR> Then it must have used some really good metalurgy in the gears?

they put drive gears inside hubs...

 MR> Was there a way to disengage the generator when not needed?

I hope so...  prolly controlled via a pull mechanism in the hollow axle
like on a three speed hub.

 -=> Bye <=-

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