[PStechPaul]

I've been thinking about these:
http://www.hobbyking.com/hobbyking/s...idproduct=4652

They are 2kW but at 193k and 37V they are 7000 RPM which is more easily geared down. $52 each with discount. But it's an outrunner. I had an idea to use six of these mounted on the axle and use 12 tooth 20 pitch pinion gears on each shaft ($12 ea). Then use a gear rack on the inside of the brake drum which is probably about 12" diameter and would have 240 teeth, cost of about $35. A This would be a reduction drive of 20:1 so the wheel would turn at 350 RPM. So using this method a 12kW wheel motor could be constructed for about $419 in materials.

It would not be too difficult to have 24 tooth and 36 tooth pinion gears on the motors and rig up a system that would shift gears by moving the motors radially and axially. These gears would add 6*$21 or $126 to get the second speed of 700 RPM and then 6*$31 or $186 to get a third speed of 1150 RPM.

This would not be a 15 minute bolt-on accessory but could be fairly easily made to replace the brake plate on the rear axle and the brake drum could be machined with the ring gear.

For caliper disk brakes you could mount the motors with the shafts on the outside of the disk, and you could just cut gear teeth on the outer circumference of the rotor. A simple machine shop operation and you retain the use of the brakes. The caliper may limit the number of motors, but you might be able to get larger ones or make do with three or four and lower power.

Here is my design for a wheel motor that I could build for a tractor application. These are three 1/4 HP (1/2 HP peak) 12VDC motors that I have. I'm showing three 12 tooth 20 pitch gears and one 60 tooth gear that is also the hub for the wheel. I'm showing an 8" pneumatic tire and wheel assembly from Harbor Freight, which has four bolts about as shown. The motors are mounted front and back on swivel arms so the pinion gears can swing out of the way. This is only a 5:1 reduction and my motors are 5000 RPM, so this will spin too fast and not have enough torque for a tractor. But this is just a concept.

[WheelMotor]

Hi PStechPaul, happy to see that you also consider using Hobbyking motors.
At 52$ for 2kW we are at 26$ per KW and the in-runner of 6KW kost only 75$ that is less than half at 12.5$/KW.
The excesive RPM of 1000RPM/V is a problem, but we connect before the diff. The Jaguar diff has a 2.8/1 reduction and a BMW 740 has a similar 3/1 reduction. So we need an extra 13/1 reduction in the trunk of the car. For this we need a 2 stage reduction of 2 X 3,6/1. That will make 2 chain gears with diameter of about 6 cm and 2 of 22 cm. but ...
It will look like this: (I made the gears proportional in dimension on the picture)

But ... the top wheel will have to spin at 40000 RPM and IF that is possible ... I will have a noisy siren in my trunk
This will happen at top speed of the system and that is about 120 km/h, question is if it will be more noisy than all the rest at that speed.

[WheelMotor]

Let's not be pessimistic, this man has a jet turbine powered scooter with a gearbox. The turbine idles at 40.000 RPM and goes till 160.000 RPM. Not sure if that wine is the turbine or the gearbox ...

[_GonZo_]

Think this will be of your interest:

http://robotics.ee.uwa.edu.au/theses...-Hooper-ME.pdf

[WheelMotor]

Originally Posted by _GonZo_

Think this will be of your interest:

http://robotics.ee.uwa.edu.au/theses...-Hooper-ME.pdf

Thanks a lot GonZo !!!
I have to go, but can't stop reading!

The article speaks about this RC BLDC Turnigy CA120-70 of 17KW at "only" 10.000 RPM !
They discuss it on Endless-sphere.com (where the picture comes from).



Hobbyking price 450USD or 360 euro

In the pdf article of "The University Of Western Australia" they conclude with proposing a WheelMotor with this Turnigy BLDC motor with gears. Very nice study! But still some way to go to make it weather prove.

[WheelMotor]

So many people are busy with electrification ...

American Warren Beauchamp has a website about recumbent Bicycles and also studies the possabilities of gearing down RC BLDC's:
This website : Recumbents.com

[PStechPaul]

I've also been looking at these motors:
http://www.ebay.com/itm/380364297736



They have a 540kV version, 5500W, 80A, but that works out to 68V and 37,000 RPM. Still, not bad for $257 including controller and free shipping. I think there is a formula somewhere about gear and belt drive efficiency. For 100:1 reduction from a high speed motor to a wheel I would guess you might have only about 70% efficiency.

This might be a better choice. It's 9HP PM 84V 4900 RPM for a starting bid of $300 + $59 shipping. But too big for a wheel motor, actually.
http://www.ebay.com/itm/170888695722
or a 2HP motor for $30 + $20 shipping
http://www.ebay.com/itm/120961125555

I still think, maybe, a multiple motor approach might be better. What is really needed is is reliable data and a good source of motors.

I found another motor that might be useful. It's 6600W 80kV 52V 4160 RPM maximum for $265:
http://hobbyking.com/hobbyking/store...ner_Motor.html

But if you can find three phase motors pretty cheap, *NEW* 1.5 HP 3400 RPM 56C $58 + $25 shipping:
http://www.ebay.com/itm/160652715791






Three of these per wheel would be 9 HP total which I think is plenty for a hybrid. $255/wheel.

[WheelMotor]

Very pleasant reading about BLDC prototyping !!!
It is in German, if you don't speak it, please open in Google Chrome and translate to your language.

http://powerditto.de/experimente.html

[_GonZo_]

I been using a lot of RC Brush-less motors and controllers for quite long time, usually they are quite good quality motors and very efficient for the porpoise they are made, that is moving propellers or small RC cars.

The efficiency is achieved because they are made with very light and open housings for cooling, thin plates on the stator in order to minimize looses, and small ball-bearings in order to save weight.
But this type of motors will not stand continuous work as they will have to do on a car unless they are modified.

As well you have to know that the power rating of RC motors and controllers is not the same as industrial ratings, with this I mean that if an RC motors is rated to give 1000W means that is able to give up to 1000W for some seconds (about 10s usually) same for the controllers.
Usually when we install RC controllers if the motor is able to pull lets say 30A we instal one that is able to give up to 50A or more and usually modified with more heat-sink added to them.

The ball-bearings on RC motors are replaced every 20-30 hours of use.

[PStechPaul]

Very valuable information! I think the same can be said for some of the cheap wheel motors and scooter parts advertised on eBay and elsewhere. They are certainly not designed to the same standards as industrial AC motors or DC forklift motors and others that are really intended for continuous use under often adverse conditions. It's really not wise to skimp on the motor or try to use something that was designed for hobby use or intermittent duty. Most of the cost and weight of an EV is still the batteries.