Bofeili Crankshaft Drive

Matthijs

100 W
Joined
Aug 25, 2009
Messages
102
Location
Amsterdam
When doing a forum search I discovered that only one guy (Nader) on this forum uses this system. He is from Germany. Are there more members that have any experience with this system?

http://www.bofeili.com
http://bofeili.en.alibaba.com/product/375710477-209381840/bike_engine.html

Build thread (Translated)

http://www.nalizadeh.com/ebike/pics/bikes.html

[youtube]lCVAGQ3CsDg[/youtube]

Edit: Here seems to be another one as well from Taiwan: http://www.bicycle-motor.com.tw/b2.html (Already in the forum: http://endless-sphere.com/forums/viewtopic.php?f=30&t=18255)
 

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Wow! Now that is a clean package! Its a hub motor with the axle being the cranks! Wait a minute, that gives me an idea! 4000 watt crystalyte crank motor anyone?!!! You would just have to replace the axle and move the wiring out of the axle and out the side of the case!
 
Why 3 times the size? Driving through the gears would make you actually need LESS power? I have looked at my hub at home and I see why this will not work without a LOT of work so it was just an idea..
 
It seems to be a good drive.
Have any one ask for price of a crankmotor ?
Need some welding to the frame but a steel frame that not so hard.
 
umejopa said:
It seems to be a good drive.
Have any one ask for price of a crankmotor ?
Need some welding to the frame but a steel frame that not so hard.

I see they are offered in Europe for € 369 + shipping. But going directly to china would be cheaper but if i saw it correctly minimum order is 100 pieces. :?

Edit: I see here: http://bofeili.en.alibaba.com/product/378512886-209381840/electric_bike_conversion_EN15194.html FOB USD 100~300 / Set

http://translate.googleusercontent.com/translate_c?hl=nl&ie=UTF8&prev=_t&rurl=translate.google.nl&sl=auto&tl=en&twu=1&u=http://www.ebike-solutions.de/epages/62204758.sf/de_DE/%3FObjectPath%3D/Shops/62204758/Products/momm01&usg=ALkJrhhKzu3Q6b_ZYdtboWH6pxRG36z4kA
 
Miles said:
Whiplash said:
Driving through the gears would make you actually need LESS power?
True, you could manage with less power. For the same power it would need to be bigger, though.


ahh I see what you mean...
 
A source for the drive unit alone > http://www.bmsbattery.com/central-motor/321-ebike-central-motor.html

ebike-central-motor.jpg

ebike-central-motor.jpg

ebike-central-motor.jpg
 
Thanks bj

* No-Load Speed 155Rpm
* No-Load Current 0.8A
* Hall Sensor Yes
* Efficiency 78%
* Normal Voltage 36V
* Phase Angle 120°
* Power 180Watts
* Rated Current 6.4A
* Rated Speed 135Rpm
* Rated Torque 12.7N.m
* Weight 3Kg

So, it can sustain an output of less than 120 Watts, at a cadence of 90 rpm......
 
I just don't get the idea that you need to make a unit only handle stupid low power like that, why not make an off road drive market it as 250 watts @ 24V and make it handle like 48 at least and the ability to take more amps? It seems there would be a fairly large following for something just like this one that could handle higher power levels like this. Hell, even 1000 watts would be enough with the righ gear range!
 
Whiplash said:
I just don't get the idea that you need to make a unit only handle stupid low power like that.......
Well, as we said, if output speed is constrained to a reasonable cadence, size and weight will be directly proportional to power required, for a given design (internal reduction ratio etc.).
 
Yes, but couldn't these companies that have the resources just build a unit with some headroom?
 
Its a bit of room to grow by adding amps or volts. Just simply build strong enough to tolerate more than the rated power so individuals can "grow" the output to their liking without total fear of destruction...
 
What Miles is eluding too is that a crankdrive offering truly useful power (>~500W IMHO) cannot achieve an acceptable size/weight unless its design separates motor RPM to levels well above Cadence RPM using some form of speed reduction/torque multiplication. The optibike drive system uses a dual stage epicyclic/planetary transmission in order to provide up to 850W in a package of similar size/weight to this POS out of China. Direct Drive crankshaft drive = fail. Not worth the cost and effort of a custom frame, or the weight and complication for a 120W motor IMHO.

Optibike 850W drive system.
IMG_1454.jpg


Patent > http://v3.espacenet.com/publication...014366A1&KC=B2&FT=D&date=20031007&DB=&locale=
 

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I like the look of these motors.

The alibaba link seems to indicate it does have planetary gearing.

1. Crank Shaft Electric Motor with Own Exclusive Patent
2. More Beautiful, more logical, more energy-saving
3. Hight Efficlency In power Conversion.(Reduce Mechanical Loss), Highly Efficient In-Line Drive.
4. Model: BFLEM36-001
5. Rated Voltage: DC 36V
6. Rated Power: 150-250W
7. Rated Efficiency: 80%
8. Our motor has a wide range of gear ratio due to using planetary gear and can be adjusted according to your demands.
9. Using Dual-rachet clutch
10. Electric power supply and manual labor are totally separated without interfering with each other, which makes the structure of electric motor more compact
11. High quality and most competitive price, and providing high-quality after services
12. DC Brushless


The OP already linked to Nader's builds and he said

It is a 350-400W very strong bottom brackets engine (Bofeili) and can be operated with both 36 and 48V.
The controller is a 15A.

Thereby is 28 mph loosely possible (with 36V) and 17% hill very easy to drive . :wink:
..and you can read and see the building process in german pedelec-forum (http://www.pedelecforum.de/forum/showthread.php?7026-Tretlagerantrieb-im-Selbstbau).
 
Ok, i didn't see that, due in part because i couldn't believe that if it did incorporate a planetary/epicyclic gearbox, that it would be so handicapped in power output.
 
Whiplash said:
Yes, but couldn't these companies that have the resources just build a unit with some headroom?


No. The part you're missing is the part Miles said earlier about needing it to be 3x larger than a hub for the same power. He wasn't kidding.

Power is a function of speed and torque. Anytime you drive through the cranks (something that actually spins SLOWER (around 1/2 to 1/3rd) than the wheels even!), you end up in a situation where for a given volume of motor, you're able to give about 2-3times more power output if you just stuck it in the wheel directly.
 
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