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Evan
05-29-2010, 02:04 PM
I am experimenting with a magnetic torque converter for the gas engine on the hybrid electrotrike. I want to mount it on the housing of the inputshaft on the transaxle. There is just enough room for the driven element but a small problem exists. The extended part of the light alloy casting has a taper because of the casting draft. It isn't much, only about .015", but I don't have room to machine a sleeve to fit over it. I am constrained by the size of the bearings I must use for the driven element. So, the solution is to machine the housing to a cylinder.

This is the housing before machining.

http://ixian.ca/pics7/inplace1.jpg

This is the single use tool I made to machine it. It is a collection of scraps from my junk box including a wrist pin from a V8, some sched 40 pipe, a 1/2 x 20 nf bolt with nut hidden inside the big tube. There is no special machining involved and most of the fits are press fits except the tool holding collar which may be adjusted to provide the correct reach and the tool itself. The wrist pin just happens to be a perfect snug push on fit on the splines of the input shaft. I love it when that happens.

http://ixian.ca/pics7/inplace2.jpg

I drove the tool with a battery drill at low rpm. It took three passes and ended up pretty decent. The now machined housing only needs to accept a custom fit bronze bearing sleeve that will have the ball bearings pressed on it. The reason for machining it is that the bronze sleeve must be able to slide back and forth on the housing nose about 1/4".

The result:

http://ixian.ca/pics7/inplace3.jpg

John Stevenson
05-29-2010, 02:12 PM
wHY NOT PRESS / LOCTITE AN INTERNALLY TAPERED STEEL SLEeve onto the engine and run the bronze bush, steel to bronze instead of bronze to crap alloy.

Also do you know where to get a decent keyboard :(

Still an interesting application though. ;)

A.K. Boomer
05-29-2010, 02:18 PM
That reminds me of a setup I had to do for the throw-out bearing boss on a Dodge colt vista, it had such a lip and was so worn I machined it down and installed a sleeve.

Black_Moons
05-29-2010, 02:46 PM
Intresting, magnetic torque converter? Any urls you could point me to on the subject? I tryed google but its mainly hard to deciper patents and such.

assumeing its two disks next to eachother with magnets on them, that seems like it would'nt (up?) convert torque at all when it slips.. if anything, lose torque.. more of just a torque limiter, with maybe a clutching action if you move the plates further apart.

But then I might be totaly assuming wrong here..

Evan
05-29-2010, 02:58 PM
wHY NOT PRESS / LOCTITE AN INTERNALLY TAPERED STEEL SLEeve onto the engine and run the bronze bush, steel to bronze instead of bronze to crap alloy.


I'm not sure I follow you. There isn't a practical way to mount anything more than an HTD pulley on the crankshaft of the engine. It isn't normally even exposed as it is designed to run an 8 to 1 reduction gear built into the engine. The pulley will also have to serve as a flywheel and that is the maximum weight the engine will take on the crankshaft. Regardless of where tha parts are I still need that transaxle nose to be cylindrical to mount a rotating element there.


As for the magnetic torque converter, it is still under construction. Here is a peek at the high value part.

http://ixian.ca/pics7/magtorque.jpg

Astronowanabe
05-29-2010, 03:23 PM
I think SJS is asking why instead of turning down the outside to a slightly smaller cylinder you did not build it up to a slightly larger cylinder.

the upside is it should be slightly stronger and more wear resistant
the only downside I see is it is a larger diameter cylinder may not fit


Did you do anything to support the hand drill side on axis or was the internal support on the work end plenty?
Just asking because it looks like there is quite a bit of leverage available on the hand end for something to go a little bit off.

MTNGUN
05-29-2010, 03:51 PM
Good job, Evan.

I would interpret Sir John's comments as a complement. He even included a "thumbs up" icon. :)

If a bushing had been machined to fit over the as-cast snout, there is no guarantee it would be concentric with the output shaft, since there is no guarantee the as-cast snout is concentric with the output shaft.

It is concentric now, after being machined in place.

Doc Nickel
05-29-2010, 04:38 PM
Intresting, magnetic torque converter?

-I was going to ask the same thing. Magnetic clutch I can see, or a magnetic torque limiter, but unless you have some ferrofluids in there and some clever electronic controls, I'm having a tough time figuring out how it could be a torque converter.

But aside from that nitpick, a clever solution to the clearance problem. And yeah, it doesn't happen often, but it's always nice when a scrap bit turns out to be the exact size you need. :D

Doc.

Evan
05-29-2010, 04:46 PM
I did'nt have room to make a sleeve as I commented in the original post. I am constrained by the bearings on the magnet wheel as those are the only ones I have with a suitable profile.

I supported the drill by hand. I have a learned skill from aircraft repair of always holding the drill correctly aligned to the work. When drilling aircraft skins you don't have the luxury of being able to use a drilling guide since most of the surfaces are curved and the skins are drilled in place. If the holes are at an angle the rivet won't upset properly and will be rejected by the inspector.

Evan
05-29-2010, 04:50 PM
I was going to ask the same thing. Magnetic clutch I can see, or a magnetic torque limiter, but unless you have some ferrofluids in there and some clever electronic controls, I'm having a tough time figuring out how it could be a torque converter.


It's an eddy current coupling. The horsepower transfer goes up as the third power of the rpm difference. That makes it a torque converter. It also acts as an automatic clutch since when the motor is driving harder than the shaft is turning it will cam the plates together. When the shaft overruns the motor it will cam back, disengaging the motor. I want the energy to regenerate the batteries instead of using compression braking.

BTW, at 800 rpm it will transfer about 2 foot pounds of torque. At 1600 that will be about 4 lbs and at 3200 it will be around 8 and at full throttle it is about 15 ft lbs. The magnets have to be in the driver plate since the driven plate can get very hot.

Astronowanabe
05-29-2010, 04:58 PM
I... It isn't much, only about .015", but I don't have room to machine a sleeve to fit over it. I am constrained by the size of the bearings I must use for the driven element. ...

and there it is. sorry, I must have been distracted by the shiny pictures.

John Stevenson
05-29-2010, 06:37 PM
Good job, Evan.

I would interpret Sir John's comments as a complement. He even included a "thumbs up" icon. :)

If a bushing had been machined to fit over the as-cast snout, there is no guarantee it would be concentric with the output shaft, since there is no guarantee the as-cast snout is concentric with the output shaft.

It is concentric now, after being machined in place.

Good point.

jkilroy
05-29-2010, 11:20 PM
Good work all around, very interested in the road test results.