New Approach to 4500W Mid Drive

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cozy35   1 W

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New Approach to 4500W Mid Drive

Post by cozy35 » Feb 08 2019 5:11am

After me previous plan for a compact, light weight mid drive, suffice to say that the synchronous belts and pulley system turns out to be a little more problematic in the way of reliability and torque handling.

My previous post:
https://endless-sphere.com/forums/viewt ... =6&t=98510

This is my new attempt for a even more compact drive by using a planetary system. I have been looking at cycloidal reduction drives as well as strain wave reducers. Both seem very expensive and way beyond the abilities of most DIY'ers

Planetary parts are readily available and relatively cheap. I for one like to use the part available from BaneBots, and I still have some gear-sets available fro previous projects.

My planetary Gear Box has a 16:1 ratio and can handle 160NM of torque.

I have also decided to use the APS (Alien Power Systems) APS8055 50K Sensored. Lower KV means more torque and less noise. This motor has enormous torque of 9.2NM.

Here are some pictures.
GearSet-001.jpg
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GearSet-002.jpg
GearSet-002.jpg (62.58 KiB) Viewed 2151 times
P80-M-Box-001.jpg
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cozy35   1 W

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Re: New Approach to 4500W Mid Drive

Post by cozy35 » Feb 08 2019 10:24am

An exploded view of the assembly.
P80-M-Box-IPN-001.jpg
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Grantmac   1 kW

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Re: New Approach to 4500W Mid Drive

Post by Grantmac » Feb 08 2019 3:14pm

Will it fit between the cranks?

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Re: New Approach to 4500W Mid Drive

Post by Andrewol » Feb 08 2019 4:47pm

Perhaps better to use APS8072 50KV for enough power without too much heat build up. With planetary reduction gear you can reconsider belt drive or direct belt left side drive. Also freewheel should be implemented to the motor. Chain combined with planetary gear will produce too much noise from the set.

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Re: New Approach to 4500W Mid Drive

Post by neptronix » Feb 08 2019 8:05pm

Nice!
Efficiency is everything :bolt:

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Farfle   1 MW

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Re: New Approach to 4500W Mid Drive

Post by Farfle » Feb 08 2019 10:36pm

Make sure that you keep the conductive materials away from the shell of that outrunner. A lot of motors oversize the magnets and under size the back iron as a weight optimization, and leak alot of flux out of the can when they do it. The flux leakage induces some serious heating in anything conductive about one to two magnet pitch-widths from the rotor.

Might want to trade that carbon shell for a FG with carbon vinyl wrap :)
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cozy35   1 W

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Re: New Approach to 4500W Mid Drive

Post by cozy35 » Feb 09 2019 12:41pm

Grantmac wrote:
Feb 08 2019 3:14pm
Will it fit between the cranks?

I have designed tot to fit between cranks with spindles 92MM and up and a Q-Factor 0f 145 and more.. It it does not fit between the cranks one can fit it outside the pedal arc.
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cozy35   1 W

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Re: New Approach to 4500W Mid Drive

Post by cozy35 » Feb 09 2019 12:45pm

Andrewol wrote:
Feb 08 2019 4:47pm
Perhaps better to use APS8072 50KV for enough power without too much heat build up. With planetary reduction gear you can reconsider belt drive or direct belt left side drive. Also freewheel should be implemented to the motor. Chain combined with planetary gear will produce too much noise from the set.
The freewheel crank is an option and I also have the freewheel sprocket on the Planetary Drive. I have used this planetary system an quite a couple of projects and the noise is less than a friction drive setup I used before.

The 8072 motor is way to long when fitted on the Planetary box to fit between the cranks.
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cozy35   1 W

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Re: New Approach to 4500W Mid Drive

Post by cozy35 » Feb 09 2019 12:50pm

Farfle wrote:
Feb 08 2019 10:36pm
Make sure that you keep the conductive materials away from the shell of that outrunner. A lot of motors oversize the magnets and under size the back iron as a weight optimization, and leak alot of flux out of the can when they do it. The flux leakage induces some serious heating in anything conductive about one to two magnet pitch-widths from the rotor.

Might want to trade that carbon shell for a FG with carbon vinyl wrap :)
Ha ha ha... I'm busted.

The FG look-alike is simply a cover to hide the ugly bolts that hold the assembly together. there is no cover around the motor and I also intend to 3D print a centrifugal fan to draw more air through the motor.
CoolingFan-SK3-6374.jpg
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tentman   10 mW

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Re: New Approach to 4500W Mid Drive

Post by tentman » Feb 09 2019 8:46pm

Hello - interesting ideas. Do you have a reference for the allowable torque on the outside end of these Banebot Planentries (I can't find one), and which model are you considering. Thanks

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cozy35   1 W

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Re: New Approach to 4500W Mid Drive

Post by cozy35 » Feb 10 2019 12:22am

tentman wrote:
Feb 09 2019 8:46pm
Hello - interesting ideas. Do you have a reference for the allowable torque on the outside end of these Banebot Planentries (I can't find one), and which model are you considering. Thanks
I am referring to the P80 model parts. I am only using their planets/sun/spur and ring gears, and not the bearing blocks or casings. I don't particularly like the rest of the gear box.

They say that 85ft/lbs should not be exceeded. I have exceeded this by almost 1.6 x in previous projects. It is also unclear if they mean that is for the aluminum ring gear set or steel set. In both cases they give 85ft/lbs as a max.

In this design, given that the max torque of the 8055 4500W motor is 9.2NM at 2590 RPM (14S - 51V/80A) and reduced 12/1 with an output speed of 215 RPM, the OP torque demand is 108NM or 80ft/lbs. So it is still within the max torque that Banebots state.
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Re: New Approach to 4500W Mid Drive

Post by Andrewol » Feb 10 2019 2:31am

Before you wrote the gear set is capable 160NM.
Any deadlines when the mid drive set will be made?
Do you prefer making it for yourself only or as GB?

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cozy35   1 W

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Re: New Approach to 4500W Mid Drive

Post by cozy35 » Feb 10 2019 4:33am

Andrewol wrote:
Feb 10 2019 2:31am
Before you wrote the gear set is capable 160NM.
Any deadlines when the mid drive set will be made?
Do you prefer making it for yourself only or as GB?
I used the hypothetical number of 160NM as a result of my findings and experience with this gear-set. As I indicated that Banebots say it should not be used in scenarios exceeding 85ft/lbs (115NM) and they do not sate if it is using the aluminum ring gear or steel ring gear. I have used it in excess of 180NM with the steel ring gear. Mostly the bearings failed and I will use better quality bearings. These gears are all case hardened. This drive should not see more than 80Ft/Lbs (110NM).

If the drive proves to live up to expectations, I may certainly make cads & parts available for other enthusiasts.

Thanks for your interest
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tentman   10 mW

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Re: New Approach to 4500W Mid Drive

Post by tentman » Feb 10 2019 11:26pm

Hello again - do Banebots have data online about the ratings of their gearsets - I can't find it . . . where/how did you get the specs (I want the specs of their bigger offerings). Thanks

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cozy35   1 W

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Re: New Approach to 4500W Mid Drive

Post by cozy35 » Feb 11 2019 11:23am

tentman wrote:
Feb 10 2019 11:26pm
Hello again - do Banebots have data online about the ratings of their gearsets - I can't find it . . . where/how did you get the specs (I want the specs of their bigger offerings). Thanks
No they don't. It is stated in the fine print in the product description. It is still strange to me why the aluminum ring gear as well as the steel ring gear has a max of 85ft/lbs.

"Taken from their site:

"MAXIMUM TORQUE RECOMMENDATION
We recommend maximum torque not exceed 85 ft-lb for all P80 Series Gearboxes. It is possible to mount motors that will exceed this in higher gear reductions. Higher reduction gearboxes should be utilized primarily for speed reduction. Designs utilizing a P80 gearbox / motor combination that will exceed 85 ft-lb should include a method of limiting torque to prevent damage to the gearbox."

http://www.banebots.com/product/P80C-3.html
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Grantmac   1 kW

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Re: New Approach to 4500W Mid Drive

Post by Grantmac » Feb 11 2019 1:23pm

With the correct input and output support one of the single stage would make a great jackshaft. You could run a 2:1 drive into it for excellent belt/chain life.

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cozy35   1 W

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Re: New Approach to 4500W Mid Drive

Post by cozy35 » Feb 11 2019 3:23pm

Grantmac wrote:
Feb 11 2019 1:23pm
With the correct input and output support one of the single stage would make a great jackshaft. You could run a 2:1 drive into it for excellent belt/chain life.
Not sure I follow?
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Re: New Approach to 4500W Mid Drive

Post by Grantmac » Feb 11 2019 3:39pm

Rather than coupling onto the end of the motor you could run a belt or chain drive to the gearbox. This would let you run a bigger motor without being overly wide.

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cozy35   1 W

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Re: New Approach to 4500W Mid Drive

Post by cozy35 » Feb 11 2019 3:58pm

Grantmac wrote:
Feb 11 2019 3:39pm
Rather than coupling onto the end of the motor you could run a belt or chain drive to the gearbox. This would let you run a bigger motor without being overly wide.
The PlanetBox plus Motor totals 116MM Plus the 14.9MM for the freewheel sprocket. So from end of motor to center line of the sprocket it is 123MM.

If I combined a single belt drive with a single stage planet system the object of a compact drive will be defeated. Then I am back to square one as my original design which i could not see a way to fit it in the "V" above the BB and clear the full suspension shock/spring.

https://endless-sphere.com/forums/viewt ... =6&t=98510

BTW, I still have to come up with a practical mount to the down tube. The majority of the forces will be taken up with plates to the BB
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Re: New Approach to 4500W Mid Drive

Post by Grantmac » Feb 11 2019 4:17pm

You might not have enough motor for the sustained output you're after.
You could easily mount the gearbox under the downtube and motor above. It's much more compact than your original series of belted pulleys.

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cozy35   1 W

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Re: New Approach to 4500W Mid Drive

Post by cozy35 » Feb 12 2019 12:44am

OK, so I've moved on and started to design the mounting. Hopefully I can come up with an ergonomic system easily adaptable to a variation of down tube sizes in both steel, aluminum and carbon fiber. I would like to have both a non- bottom bracket and bottom bracket mount system. I think I can do this.

I was concerned as some people shared their concerns, suggestions ad advice. (Thank you) I am still convinced that the Planet Box is still the most compact in all axis' and given the off-the-shelf availability of planetary parts and ease of building for the DIY'er, should make this an interesting project. I designed the box so that all parts can be laser and/or water jet cut, eliminating the need for expensive shop machining. I know that some shops do not like to laser cut aluminum stock thicker than 2.5MM because of the burring and would rather water jet cut these. Just a load of thread tapping is needed and can easily be done by hand.

I have the mounting dimensions down to as much as to fit between cranks of not less than 145MM, by going for a 4th chain-ring on the outer side. ( in the case of a 3 chain-ring setup.) I am using a Diamond Back Vector 2007 MTB as a platform and it has a 68MM BB. Any BB that is wider is a bonus and makes fitting even easier. I will not be using a chain tensioner because of the close proximity of the O/P free wheel sprocket to the driven chain-ring and I think would be superfluous.

Here is a picture of the fitting measurements:
P80-M-Box-Measurement.jpg
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cozy35   1 W

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Re: New Approach to 4500W Mid Drive

Post by cozy35 » Feb 12 2019 1:02am

Grantmac wrote:
Feb 11 2019 4:17pm
You might not have enough motor for the sustained output you're after.
You could easily mount the gearbox under the downtube and motor above. It's much more compact than your original series of belted pulleys.
I don't believe that this setup would ever exceed 3000 Watts. The motor I am using is rated 4500 Watts and has 9.2NM torque and can handle up to (14S @ 4.2V/Cell) 58.8 Volts @ 80 Amps. I plan on maximum of 50.4 volts @ 50 Amps. So my maximum power use will not exceed 2400 Watts. Calculations show a maximum speed of 60 Km/Hr on an incline of 5%. (I hope I did not make a calculation error)
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Re: New Approach to 4500W Mid Drive

Post by cozy35 » Feb 12 2019 2:45am

The BB mounting plates and a remodeled Box End Plates are done, and now for the saddle to down tube mount. I think I will have to make a spreadsheet to determine the various required spacers to cater for the different BB spindle sizes. The saddle mount should be a universal fit for down tubes from 30MM and up and also for some odd size carbon frames.

Here is a pic without the saddle mount:
P80-M-Box-BB-Brackets.jpg
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Re: New Approach to 4500W Mid Drive

Post by silence » Feb 12 2019 8:38am

Pretty clever. Really like it.
Something like reasonable man's Tangent drive. :)

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cozy35   1 W

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Re: New Approach to 4500W Mid Drive

Post by cozy35 » Feb 13 2019 5:26am

I have been toying with an effective mount that will not destroy carbon frames. For that I steered away from conventional U-Bolts and metal clamps. Carbon frames do not take kindly to these methods.

I decided to use Polyester Webbing Belt material for this. It will also protect paint finishing and not damage a bike frame. Here is a pic of what it may look like:
Mount.jpg
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