Ultimate lightweight wheel-motor concept
- Thread starter speedmd
- Start date
+1
It would take me about a week to draw those...
With covers, how much room is there (diameter/width) regarding the chainstay? My bike may have narrower stays than is typical.
Good point on the back iron. I'd assumed it wasn't an exotic material. Rethinking it, your clamping bolts idea may be best. Ideally they'd bottom out (or have a tube between the covers) so they can be torqued down without bending the covers. A locating lip on the inside of the covers (if possible/practical?) would finish the job.
Really not sure about FWD... Can't help thinking that the centre of the rear wheel is the best place for a motor. Especially if you want a torque-monster.
It would take me about a week to draw those...
With covers, how much room is there (diameter/width) regarding the chainstay? My bike may have narrower stays than is typical.
Good point on the back iron. I'd assumed it wasn't an exotic material. Rethinking it, your clamping bolts idea may be best. Ideally they'd bottom out (or have a tube between the covers) so they can be torqued down without bending the covers. A locating lip on the inside of the covers (if possible/practical?) would finish the job.
Really not sure about FWD... Can't help thinking that the centre of the rear wheel is the best place for a motor. Especially if you want a torque-monster.
Punx0r said:
yes, for the clamping method of the carbon discs we should use screws with big heads reach across the notch. This way the covers will not bend much.
i was thinking about a back emf ring made out of a steel strip welding it together (simple and cheap), but i think this is not very precise and the magents will become loose if the ring gets bend.
motor better to the rear wheel and not to the front
The more I think about it the more I like the cassette motor
You can dish the motor so it tucks in tight to the spokes where they narrow to meet the rim
Much easier to service
Rwd which eveyone likes
Cheaper to make (no custom hub that wont work for everyone, no worry anout spoke length, etc)
More optionality (dual drive, freewheel, no freewheel, thousands of hubs)
Not a copy of the d series but still retains all the advantages
It doesnt matter it is not in the center of the rim as the power will still be translated through the spokes in any case
With an inrunner we gain good heatsinking as is (no messing with oil, easy to add water cooling for a cargo or race bike), dead simple wire routing (think huge phase wires), and more optimal placement of torque arm(s)
Plus it doesnt look like a dorky magic pie
Now make it work for a 700c and 26" rims
The two most common
Universal fit kit
Naturally it will also work for 20 inch race bikes 8)
You can dish the motor so it tucks in tight to the spokes where they narrow to meet the rim
Much easier to service
Rwd which eveyone likes
Cheaper to make (no custom hub that wont work for everyone, no worry anout spoke length, etc)
More optionality (dual drive, freewheel, no freewheel, thousands of hubs)
Not a copy of the d series but still retains all the advantages
It doesnt matter it is not in the center of the rim as the power will still be translated through the spokes in any case
With an inrunner we gain good heatsinking as is (no messing with oil, easy to add water cooling for a cargo or race bike), dead simple wire routing (think huge phase wires), and more optimal placement of torque arm(s)
Plus it doesnt look like a dorky magic pie
Now make it work for a 700c and 26" rims
The two most common
Universal fit kit
Naturally it will also work for 20 inch race bikes 8)
speedmd
10 MW
Plus bike loads are not trying to smash the gap and destroy your hard work. I do worry ideally we may need to beef up the freehub a bit. This is starting to look like a great general purpose light weight design outline that can have mass adaptation. Bravo to the brain trust! We should bounce around some of the best stock hub options a bit.
We should bounce around some of the best stock hub options a bit.The hub is whatever
The quesion now is the case with torque arm mounts and how big we can make it and still fit all bikes 20,26,29(700cc
Machining a huge chunk of inch thick alumnium to press fit them 300+mm wide 20 mm long stator in wont be cheap but we the best and for just a bit more add fins all around
We need somthing easy and just as good (direct thermal contact)
The quesion now is the case with torque arm mounts and how big we can make it and still fit all bikes 20,26,29(700cc
Machining a huge chunk of inch thick alumnium to press fit them 300+mm wide 20 mm long stator in wont be cheap but we the best and for just a bit more add fins all around
We need somthing easy and just as good (direct thermal contact)
Have a look at my cross section view, PunxOr.Punx0r said:The dishing idea is a smart solution to the space problem
However, it will require dished side covers and stator frame? so no more simple parts cut from Al and CF sheet
Sorry Miles, I'm not sure quite what I'm looking at? I see the stator but am having trouble making out the casing (if present?). When dishing was mentioned I jumped to the assumption (perhaps incorrectly) that the motor profile would follow the line of the spokes.
Ok. I need to add more colours... The casing isn't modelled but space is allowed for it.
The bounds on the active motor width are set by the case OD against the chainstay and the ID of the rotor back-iron against the spokes. In practice a simple offset inwards from the rotor support plane suffices - no dishing is needed.
The bounds on the active motor width are set by the case OD against the chainstay and the ID of the rotor back-iron against the spokes. In practice a simple offset inwards from the rotor support plane suffices - no dishing is needed.
speedmd
10 MW
Does the stator need two side covers? Or more like, two structural ones.
speedmd
10 MW
For starters, most likely turned from plate. Possibly long term to use spun thinner plate depending on hub/ bearing config.
speedmd
10 MW
Cast material will give up some strength, elongation and impact resistance. You will need the ribs to gain back some of it. But you could cast in torque arm anchor and other details. Patterns / permanent mold casting will start to save you on lots of 500 or more. Finish is always a issue on castings also. Powder coat looks good.
speedmd
10 MW
I think you will need a double row bearing for certain on the rotor here. I think the Joby is that way also. Hard to maintain concentricity without that. On the stator it will torque/ move significantly without a second bearing also I am thinking. As long as the torque arm anchor can hold on without chaffing up the frame it may not be a issue. It is all dependent on the freehub play without a good mount and second bearing.
speedmd
10 MW
I am no expert, but suspect that road surface undulations will require us to maintain tighter control of the gap. This will be banging down the road and will see some significant g forces when hitting bumps / holes and such. Just a gut feel here for me.
Miles said:
if the bearings are located only on one side, it would mean the motor is not closed. I think we should make it closed to keep out dirt and water. there is not really a need to leave the case open for cooling, if we make some fins around the outside of the case.
use only one bearing is not a good idea. maybe it will work because of the very slim rotor, but it will wear down very quick and the rotor will begin to wobble soon
why not turning an AL part for the inner side to close the gap between the inner bearing and some straight carbon disc for the rest of the case?
one more part to machine, but still simple with the carbon / al discs
Yes we are basically building a JOBY motor, but we don't need as heavy duty a bearing arrangement since we won't be spinning a propeller. The rotor has the cassette as a bearing so if the case could be made to "float" around it connected to the frame...lighter but not universal. The frame mounting should not be critical to maintaining the magnet to stator gap
The motor should be supported on one side only, the outside, with a bearing to maintain the gap clear (maybe either one deep groove bearing or two normal). The cover should have threaded holes all around to various people can offer torque arms for specific frames. We can make a kludgy universal torque arm that bolts to the caliper mounting tabs on the frame to start but custom will be better.
The inside cover can be super thin whatever and be stamped or vacuum or pressure formed (the inner cover has to be dished). We want a cover to also reduce wind age losses in addition to keeping out dirt/water/dust/pebbles
Also we want the fins facing the same direction as travel (rotate the joby fins 90 degree). Taking this idea into account the aluminum stator frame ring could be sheets of Al waterjet cut and staggered to form the fins...this way no $$$ to machine from block, precision cast, or cast and machine. Quick to prototype
ring with x diameter
ring with x diameter +15mm
ring with x diameter
ring with x diameter +15mm
ring with x diameter
ring with x diameter +15mm
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The motor should be supported on one side only, the outside, with a bearing to maintain the gap clear (maybe either one deep groove bearing or two normal). The cover should have threaded holes all around to various people can offer torque arms for specific frames. We can make a kludgy universal torque arm that bolts to the caliper mounting tabs on the frame to start but custom will be better.
The inside cover can be super thin whatever and be stamped or vacuum or pressure formed (the inner cover has to be dished). We want a cover to also reduce wind age losses in addition to keeping out dirt/water/dust/pebbles
Also we want the fins facing the same direction as travel (rotate the joby fins 90 degree). Taking this idea into account the aluminum stator frame ring could be sheets of Al waterjet cut and staggered to form the fins...this way no $$$ to machine from block, precision cast, or cast and machine. Quick to prototype
ring with x diameter
ring with x diameter +15mm
ring with x diameter
ring with x diameter +15mm
ring with x diameter
ring with x diameter +15mm
ring with x diameter
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