Shaft connection problem

[oskari]

Newbie here with a problem (I´m not sure if this forum is really for profs, but since there was a free entry...):

I have a 50 kW electric vehicle traction motor I´d like to use in my future ev conversion. The motor was originally attached to a special transmission, that´s why it has an unusual shaft with helical splines. It is hollow all the way to the other end of the motor. The shaft was propably a sun gear with planet gears around it:

http://www.havina.fi/motor.htm

This is propably the same motor, or very similar, with the original gearbox:

http://tinyurl.com/247h28

So, I´d like to use this motor with a normal ICE tranny (no clutch). What would be the best way to attach the motor shaft with the tranny shaft?

1.with a coupler with inner helical gears in the motor end
-expensive?
-is there a danger the helical gears will "push" the coupler off of the motor shaft (sorry my english) > axial force stresses the tranny shaft bearings?

2. freeze joint a coupler into the hollow motor shaft
-will it hold (max 200 Nm torque)

3. ??


Appreciate your help,
Oskari

 

[MikeHalloran]

2. The motor shaft wall is relatively thin. Any number of expansion type couplings could be made to grip the inside, but they would also be at risk of fracturing the shaft.

1.a. Yes, the helix angle would push a coupling off, or try to. In order to prevent that, I'd run a tie-bolt or two from the coupling through the motor shaft to a thick washer on the other end.

1.b. Yes, a coupler with internal helices would be expensive. So, cast the helices in place. Make a steel coupler in the general shape of an internally fluted cup, with some axial grooves (e.g. bore parallel to the axis at the gear tip line), make it a nice fit to the gear outside, push it on, dam up the spline ends with clay, and lock the coupling to the splines by filling the interstices with low melting point alloy or solder through radial holes.

0. Yes, the forums are for professionals. Most ignore hobby questions, and purge student questions. Since you weren't quite dumb enough to admit that you are in fact a student, I'll assume that you are a young engineer working on a technically relevant and socially significant project. Try to get some local help, e.g. an engineering student, figuring out how thick the steel parts need to be, and if bismuth will be strong enough, or if you'll need solder, or tin, or unobtainium for the locking alloy.



Mike Halloran
Pembroke Pines, FL, USA

 

[oskari]

No, not a student, just a middle-aged hobbyist... So apparently I should just settle for reading other posts only.

Thanks for your reply, anyway.

 

[IceStationZebra]

My first inclination would be a two tiered approach. Machine a shaft with 1. An interference fit relative to the ID of the motor shaft. Freeze it and slide it in. 2. A flange with an OD at least equal to the OD of the splines. After inserting the shaft weld it on. Should be fine.

Another idea, depending on your transmission plans, would be to weld half of a LoveJoy coupler to the shaft.

Third, mind the overhang with regards to the motor bearings. The original planetary set-up is easy on the bearings but yours may not.

Fourth - what ever you do make sure that you can still service the motor bearings. If you permanently attach a large flange to the shaft and your bearing goes out you will need a new rotor/motor.

In your first picture (

http://www.havina.fi/motor.htm)

the gear is a different color than the shaft, it looks like the gear was somehow fitted onto the shaft. I relize that the picture is not of your motor, but if the detailing is the same see if you can get the gear off and than make your own with whatever spline you like.

ISZ

 

[thundair]

What direction is the motor turning will it try to screw itself on or off?

I would use and expanding mandrel on the inside and maybe a slip fit over the gear. You could use a socket head screw in the center of your new flanged adapter to expand the mandrel. Locking it up with a lot of pressure.

Its all so simple on paper.....

Cheers

I don't know anything but the people that do.