More drive-train planning

Post date: Apr 5, 2013 7:54:19 PM

After testing the mock-up adapter plate, we figured that it would be a hassle to continue the plan to put the two brushless motors in line as they are. Instead of trying to couple to two axles, it would be better to essentially replace both axles by a single new one, with a metric diameter.

We carefully disassembled one motor to figure out how realistic this would be. The pictures and info from ripperton-electric-track-bike-41173p20.html were a great help.

An automotive puller tool is handy to be able to slowly lift the stators away from the rotor disc. Initially, we removed the screws that hold the stators to the motor's enclosure, only to discover that the stator was now firmly stuck against the rotor magnets...

Eventually, with all parts separated, measurements could be taken and a new plan took off. What if we could just re-combine all components and make a single integrated motor out of it? The cooling of the stators could also be addressed. Of course, we only have limited metalworking tools, so it was essential that the design would not be too complicated. Below is what we ended up with:

The stators are held by 200x200x10mm aluminium plates, spaced apart by means of M10 threaded rods. At the center is a new axle, 22mm dia, held by two SKF 62/22-type bearings in the outer plates. Circlips on the axle prevent axial movement when the rotor magnets are pulling on it.

The idea to rotate the rear stators by 7.5 degrees relative to the front ones was axed, to simplify the construction and avoid having to deal with two separate Hall position sensors.