i have been brainstorming about building a new ebike for riding in the rain
i know this topic has been discussed before however i figured i'd share my solution
this issue has been discussed
https://endless-sphere.com/forums/viewtopic.php?f=30&t=34135
https://www.youtube.com/watch?v=gwlbAJLzI_w
in short - the hub motor is a pressure vessel- heat generates pressure outwards and cooling creates a pull effect sucking in moisture/water etc
the solution is to either create a perfectly sealed hub or cut holes into the cover to eliminate this pressure-
At first i entertained the idea of creating a perfect compression vessel like a keg-
i speculated there are 4 places of entry into a hub which are cable, bearing seal, outer rubber seal, outer edges of side covers, gap in the axle between the wire and sheath.
on my first experiment to figure out where the weakest link was i sealed a hub motor completely at the cover seals with rubber silicon glue- put a co2 line on the hole of the axle- dropped it in a bucket of water to find out that the gas bubbles were leaking from the bearing/rubber seal- go figure. so the rubber seal is useless( they are water resistance not water proof) , and bearing seals were never meant to be a barrier. I suppose if one could replace the weak rubber seals with O-ring and fabricate a metal piece to hold it in place this would provide a good vacuum with the cable being the only way for pressure to get in and out. But the cable can also be solved by using epoxy in the axle- and putting in solid stranded wires covered in adhesive lined shrink tube to eliminate any flow through the power cables altogether - creating a perfectly sealed hub.
However i don't believe this is the solution- the pressure will eventually break down the seals.. bionx implemented this solution and i've seen their hubs rust out
the real solution is to eliminate the pressure at the hub level - doing so also stops sucking and pressure through power cables which will eventually corrode it unless those cables were sealed like i described above. But even if the axle was not sealed theoretically there should not be any pressure going through those cables if the pressure is eliminated on the hub level.
creating holes in the covers presents some drawbacks such as dirt/debris getting into the hub and not being able to store the bike outdoors.
but instead of just cutting large holes in , the better solution is to use gore vents- or even better cut the holes into the cover - order some gore fabric and glue it on the outside of the holes. This seems to be a good solution as the fabric allows moisture to depart, blocks water, moisture, and dirt from getting in and eliminates the pressure problem. You also get a nice window to allow the motor to run cooler.
so ultimately installing a better rubber seal, blocking the axle (heat shrink tubing on the axle where the solid wire leaves axle), and holes in cover with gore vents offers a good solution to riding in the rain.
note; also coating the insides is a must
http://www.gore.com/en_xx/products/venting/protective/protective_vents_why_vent.html
leaving the holes bare is possible - however for those concerned can drill a hole and use the adhesive vent
http://www.gore.com/en_xx/products/venting/protective/protective_vents_product_comparison.html
http://www.hitechseals.com/products/oil-seals-SL-met.asp?lang=
http://www.skf.com/pk/products/seals/industrial-seals/power-transmission-seals/radial-shaft-seals/index.html
http://www.tokez.com/en/industrialseals.html
i know this topic has been discussed before however i figured i'd share my solution
this issue has been discussed
https://endless-sphere.com/forums/viewtopic.php?f=30&t=34135
https://www.youtube.com/watch?v=gwlbAJLzI_w
in short - the hub motor is a pressure vessel- heat generates pressure outwards and cooling creates a pull effect sucking in moisture/water etc
the solution is to either create a perfectly sealed hub or cut holes into the cover to eliminate this pressure-
At first i entertained the idea of creating a perfect compression vessel like a keg-
i speculated there are 4 places of entry into a hub which are cable, bearing seal, outer rubber seal, outer edges of side covers, gap in the axle between the wire and sheath.
on my first experiment to figure out where the weakest link was i sealed a hub motor completely at the cover seals with rubber silicon glue- put a co2 line on the hole of the axle- dropped it in a bucket of water to find out that the gas bubbles were leaking from the bearing/rubber seal- go figure. so the rubber seal is useless( they are water resistance not water proof) , and bearing seals were never meant to be a barrier. I suppose if one could replace the weak rubber seals with O-ring and fabricate a metal piece to hold it in place this would provide a good vacuum with the cable being the only way for pressure to get in and out. But the cable can also be solved by using epoxy in the axle- and putting in solid stranded wires covered in adhesive lined shrink tube to eliminate any flow through the power cables altogether - creating a perfectly sealed hub.
However i don't believe this is the solution- the pressure will eventually break down the seals.. bionx implemented this solution and i've seen their hubs rust out
the real solution is to eliminate the pressure at the hub level - doing so also stops sucking and pressure through power cables which will eventually corrode it unless those cables were sealed like i described above. But even if the axle was not sealed theoretically there should not be any pressure going through those cables if the pressure is eliminated on the hub level.
creating holes in the covers presents some drawbacks such as dirt/debris getting into the hub and not being able to store the bike outdoors.
but instead of just cutting large holes in , the better solution is to use gore vents- or even better cut the holes into the cover - order some gore fabric and glue it on the outside of the holes. This seems to be a good solution as the fabric allows moisture to depart, blocks water, moisture, and dirt from getting in and eliminates the pressure problem. You also get a nice window to allow the motor to run cooler.
so ultimately installing a better rubber seal, blocking the axle (heat shrink tubing on the axle where the solid wire leaves axle), and holes in cover with gore vents offers a good solution to riding in the rain.
note; also coating the insides is a must
http://www.gore.com/en_xx/products/venting/protective/protective_vents_why_vent.html
leaving the holes bare is possible - however for those concerned can drill a hole and use the adhesive vent
http://www.gore.com/en_xx/products/venting/protective/protective_vents_product_comparison.html
http://www.hitechseals.com/products/oil-seals-SL-met.asp?lang=
http://www.skf.com/pk/products/seals/industrial-seals/power-transmission-seals/radial-shaft-seals/index.html
http://www.tokez.com/en/industrialseals.html