Hub motor concept design

[Freshair]

Seems that hub motors are all the rage right now, and are something I have been pondering about for a while, and now that I am working with cnc equipment for work it is even more practical for me to try some things out.

Stielz hub motor gave me the confidence that the electric motors themselves may be able to take some abuse, and he reckons he has put 300km on his turnigy 6374's. With a motor with better bearings than the turnigy, this may prove to be a very reliable option. Think that his way of doing it can be improved a little, and am still not sold on glueing the urethane to the motor as the only way to secure it. Still pondering some ways to mount it a little more solid, think I may have thought of a way but wont really know tell the motors are in my hands to tinker with.

I already have a set of Rojas Hybrids with round steel hangers, and basically what I want to do is get an alien systems 6374 motor with 10mm shaft, turn 8mm part of the rojas hanger back towards the pivot a little ways and make a 10mm threaded collar for the motor to sit on that will slide over top of the 8mm section of hanger. This collar will be threaded where the nut would normal go on the hanger, so that the collar can be tighten against the hanger. Also, the collar will be threaded all the way threw towards the outside of the hanger so that a set screw can be screwed into the collar as an extra jam to hold the collar from backing off of the hanger.

Have attached a pdf file of a simple sketch up (poor mans cad) drawing that may help as a visual.

Let me know your thoughts.

 

[777arc]

I don't quite understand the set screw in the pic

 

[Freshair]

The collar being hollow so that it can slide over top of the 8mm section of hanger, will be hollow all the way threw with threads inside so that it can be tightened on to the hanger, these threads will continue out the end of the collar so that a set screw can be screwed into to the end of the collar, thus jamming up against the 8mm hanger on the inside of the collar. Am hoping this will be enough to lock the collar into place.

Sorry for the crappy design pictures, will attempt a better design soon with a cutaway so that you can see what is going on inside.

 

[Freshair]

Well don't have access to autocad at work, so I used the program I do have to make a better design of the collar. This should give an idea of what is going on. It will be simple to make and should prove effective so long as I can keep it from unthreading from the motion of the motor.

 

[Freshair]

Did a cross section model of the new design with fancy fluorescent colours :wink:

The wheels are 107mm

The motor is a 6374, but will basically only be using the stator, magnets and can with everything else machined at work

There will be 15x35x9 angular contact bearings used so that pressure can be applied to the bearings to help hold everything together, these should also provide enough strength to withstand a good beating from slides and hard cornering. The design does not show it, but will have a lip at the edge of the can to press against the sides of the wheels, and will probably do something similar to the monolith to secure the wheel from spinning.

Basically am trying to design this around the Rojas Hybrids with little to no modification required, and easy to take apart and service. There will however need to be a flat spot machined or filed into the hanger for the set screw to hold the main collar from spinning.

With no modification required it allows me to carry two spare tires and take the motors off at will and ride it like a normal board, which is useful for the case of running out of juice and having to push home or for wanting to have some fun pumping.

To me the Rojas are an all around truck that with a simple bushing change, can have you pumping one moment and bombing the next.





View attachment 2

On a side note, are there any big reasons why nobody uses battery bags? Seems like a good way to make more space for battery power and keep the weight off the board. Perhaps the leash is just not a desirable feature?

Let me know what you all think, and please do critique at will

 

[chuttney1]

On a side note, are there any big reasons why nobody uses battery bags? Seems like a good way to make more space for battery power and keep the weight off the board. Perhaps the leash is just not a desirable feature?

I remember there was one company that used a cable for the throttle. Don't remember if they did with the battery pack. Never really did take off. The leash is kind of a turn-off, especially to use long wire to the batteries. Seem like an accident is waiting to happen with the long wires getting caught on a object with a hook-like shape while riding.

 

[Vanarian]

You don't get it, this has nothing to do with the "kinda let down" of having a long wire running from the board till a bag.

The issue since we use powerful brushless motors which requires to be fed with high current is that you cannot afford to plug highly powerful batteries through long cables. If you do, you end up with a phenomenon called power surge, it's like an electric spike which damages everything. It kills your batteries, it kills your ESC. You want to get your batteries as close as possible to your ESC. :wink:

 

[Freshair]

Thanks vanarian, figured there was a good reason why

 

[torqueboards]

@Vanarian - What distance were you suggesting? Boosted seems to have at least over 15" from battery to ESC since they route their battery cables through the top of their deck. And/or couldn't you just add a capacitor bank because of the added distance?

 

[Vanarian]

@Vanarian - What distance were you suggesting? Boosted seems to have at least over 15" from battery to ESC since they route their battery cables through the top of their deck. And/or couldn't you just add a capacitor bank because of the added distance?

Maybe I misunderstood what Freshair meant by "bag" but I was referring to a backpack type bag, so with batteries on your back instead of on the board.

So this refers already to a cable length of over 1 meter (for me it would be even more since I'm tall), which is far too much if you want to burst some juice.

15" on a Boosted seems reasonnable, plus I think they use LifePo? I assumed that batteries here would be LiPo but actually I don't know if Li-Ion and LifePo are more stable in this department Need to check this.

 

[Hummina Shadeeba]

I read a sine wave controller you can have battery wires as long as you want but they're expensive and don't give quite the power

 

[chuttney1]

You don't get it, this has nothing to do with the "kinda let down" of having a long wire running from the board till a bag.

The issue since we use powerful brushless motors which requires to be fed with high current is that you cannot afford to plug highly powerful batteries through long cables. If you do, you end up with a phenomenon called power surge, it's like an electric spike which damages everything. It kills your batteries, it kills your ESC. You want to get your batteries as close as possible to your ESC. :wink:

Well that certainly explains why it never happened. I always thought the long wires were of no interest to the public and it explains the reason to put capacitors on the wires leading to the ESC.