PowerWheels 2014 Drivetrain Ideas

Brushless DC Motor

RC

• Repurpose outrunner brushless DC hobbyist motor for car/boat
• Overview of this technique for scooters
• Requires motor (2 motors?) and motor controller
• One recommended part supplier

Advantages

• Definitely the best weight/performance/efficiency ratio

Disadvantages

• Not as straightforward electrically
• Overkill?
• More expensive than hacky solutions ($200ish) (However people in town may have parts for us?)
• Less known about how to do this
• Tend to be fast RPMs so big amount of gearing down

Washing machine

This is the same idea as the RC motor except that we repurpose a washing machine motor instead

Advantages

• These motors and big and cool looking. We will look totally rad
• Unique, innovative

Disadvantages

• What voltage do these run on? Likely we will need to rewind coils?
• Motor controller might not work out-of-the-box. (What do we do, set for "spin cycle?" We have to make our own or hope for the best for a commercial unit?

Hydrostat

• Use 12V pump from Harbor Freight ($30ish each) to pump oil to turbine

Power Steering Pump as Turbine

• Needs to be vane pump. Most but not all PS pumps are vane. Disassembly Video
• Pumps available from salvage years for $20ish. Some are pick/pull and some are not. Price is the same
• Vanes in PS pump fly out from centrifugal force.
• Must use lubricating liquid

Advantages

• Innovative/unique
• Could be cool to use transparent pipes plumbed all over the place so people can see the hydraulic action. Put glittery stuff inside the fluid
• CVT Transmission!

Disadvantages

• Getting the balance between pressure and displacement of liquid likely to be tricky
• Extra weight/parts that are totally unnecessary
• Efficiency? Likely low
• Only 1 example found of using a PS pump as a turbine (MIT project) and that example was a report and not explained in detail.
• Not much reference in using vane pumps in general as turbines. Does this mean it's a bad idea?

Wheelchair System

• Use 2 motors from one of the 3 wheelchairs we already have.
• Use the intended motor controller for the wheelchair
• Re-gear the motor for more speed and less torque

Advantages

• Might be the easiest/cheapest way to go, since we already have motors and a motor controller

Disadvantages

• These motors are built for battery efficiency over hours and not for speed. Are they strong enough? Will they be fast?

Traditional Scooter Motors

• Use a couple of traditional permanent-magnet scooter motors

Advantages

• This is the standard solution by other teams. It's tried, tested, and works

Disadvantages

• Doesn't really take advantage of the parts we happen to have on-hand
• Not as fun a solution as others?

Bicycle Components

With any of the above solutions, we may need to gear down-up. Bicycle components may be a way to do this

• Use crank/sprocket/derailleur with bicycle wheel to get the right gearing
• With wheelchair motors we could attach large gear from crank to motor shaft. There are good ideas on Instructables about how to do this.
• Scooter motor distributors sell small gears that fit on motor shafts which are compatible with bicycle chains.

Advantages

• Takes advantage of parts that we probably already have around. A super cheap way to go
• Easily change gear ratios so we can find the best combination without knowing what we are doing. :-)

Disadvantages

• Thin tires. Could this cause traction problems?
• With wheelchair we would be gearing down then gearing up. Not very efficient?
• Slightly less efficient than a direct-drive solution