| Author | Message | ||
     Posplayr |
Oil cooling approaches http://www.venturers.org/Tech_Library/?action=arti cle&cat_id=001007&id=413 http://www.jetav8r.com/Vision/Stator/Stator.pdf Stators Cooling l Stators Cooling by Mark Moreland Just found this site. Read a few dozen messages but did not see a suggestion on stator cooling. I was an REV member about 1990. I obtained several years newsletters. One had a tech tip that suggested adding an oil spray orifice to the bolt in the oil gallery of the stator end of the crankshaft. I recall the orifice was drilled at ~.040" dial, and was counter bored larger to help break up a stream and make the oil sling outwards to the stator. Does anybody recall this? l Red: stator cooling by Chris Arrowroot I've seen that fix too, but I can't believe spraying hot oil on the stator would improve its situation. l Oil Cooled Stators by Dale The Vision's stator is already oil cooled, but the flow is too limited or not even, resulting in the over heating at high Ramps. Increasing the oil flow would help but I have no idea as to how to make sure that it is flowing (in and back out). l Possible source for this stator cooling tip by John Logan I do not know whether drilling the rotor bolt helps the stator longevity problem, but I have a clipping from the March, 1984, issue of Rider Magazine discussing a similar fix for the Venture, which is very much like a fourcylinder version of the Vision: "One of the foremost problems acknowledged by Yamaha has been stator failure. The alternator has been running in an insufficient oil bath, which has caused the stator wires to overheat and short out. Ours failed at 11,500 miles. Most have been giving up at around the 8000- to 10,000-mile mark. In order to lower the operating temperature and increase the reliability of the AC generator, an improved rotor bolt with a 0.7 mm [0.0276 inch -- JAB] oil passage must be installed. This supplies additional oil to the generator area to cool the rotor and stator. An improved [Venture] stator has been designed for '84." I'd be interested to know if anyone has experience with this type of fix for the Vision or has examined the improved rotor bolt for the '83 Venture. If the latter just has a bore through its center, that should be easy to accomplish. Note that the article's bore is smaller than the value Mark gave. I would be worried about effects on oil pressure -- does anyone have information about this? http://books.google.com/books?id=FzHgWqRZ_moC&pg=P A102&lpg=PA102&dq=oil+sprayer+for+stator&source=bl &ots=0HGi1A4xYS&sig=cTTcQ8Dsu3Zuvz6nvNCiXoEJXvU&hl =en&ei=sklDTrLaA8mKsQKZtJzLCQ&sa=X&oi=book_result& ct=result&resnum=6&ved=0CHkQ6AEwBTgK#v=onepage&q&f =false read about cooling approaches an oil spray is highly effective according to the table. | ||
| Sparky |
Could this be what Steve_A hinted at a little while back or was it oil jets aimed at the stator? | ||
| Posplayr |
On my GS it was pretty clear that the bottom of the stator that was closer to any oil coming up from the pan, was fairing better than the top of the stator which was getting much browner. I added an oil line (near the top) with something like a 0.060" orifice to limit the quantity of oil going into the spray and this immediately improved the situation for the stator. Later I moved to a SERIES R/R so the oil sprayer was not necessary. | ||
| Dannybuell |
When Steve_a posted I imagined a rotor with louvers used as scoops dipping from the oil bath. Centrifugal force and louver angle would target the stator. | ||
| Zac4mac |
My take also Danny. Still waiting for MORE INFO!!!  | ||
| Kinder |
Speaking of approaches.... The guy who did my rewind suggested not coating the stator. Its not like it needs it for corrosion or anything so why coat it with stuff that while it can help repel heat it also retains heat inside. The stator still does get hot after all.  Gonna try it this weekend. Will advise. | ||
| Nuts4mc |
I suggested a while back to knurl (with one knurling wheel) the O.D. of the rotor...to form "threads" in one direction to sling oil against the outer cover kinda like an oil slinger ( http://articles.compressionjobs.com/articles/oilfi eld-101/3240-lubrication-oil-field-pumps-turbines- compressors?start=2 )...a good machinist with experience on a lathe could build a spud to drive the rotor and an insert to fit inside the large ID to hold it steady ...a light knurl maybe all it takes...the question we need to ask I'm afraid: IS the Oil LEVEL high enough to be acted upon by the "slinger" technique- need to build a plexiglass rotor cover! | ||
| Sparky |
I'm not clear on the concept of knurling the outside of the rotor. Doesn't the stator fit inside the rotor? How is oil slung off the outside of the rotor going to get to the inside where the stator lives? If anything, oil should come from the center of the rotor nut, spread out past baffles properly positioned, where upon the oil would get flung directly on the stator coils like was described in the Yamaha stator cooling article Posplayr posted. I like the way you think though. I want to believe it would work. | ||
| Kinder |
The knurling would be on the inside to spray oil on he stator I presume. | ||
| Nuts4mc |
in the old days - look at a old oil filled ignition coil - or even a large transformer - the oil is a "medium" to convect heat to the outer case - in our case.. heat from the windings (stator) is transferred to the outer cover which it is bolted to...if we could cool the case (side cover)with oil it will draw heat away from the stator. ( hence the external knurling to splash oil against the inside of the cover) I don't believe you could knurl the ID of the flywheel without adversely affecting the performance of the electrical generation (trying to knurl an exposed magnet would cause it to crack)....the "air gap" would change... a difficult dimension to maintain the smaller it gets. another approach would be to build a side case/stator/flywheel cover with cooling fins, but would most likely need a scoop to direct air thru the fins to gain efficiency. or a water jacket to cool the cover....or a another type of "jacket" to circulate oil thru (the oil cooler lines are close by)...just brain stormin' here ...any combination of the above (Knurling and fins/cooling jacket) and any critique of the ideas are welcome! | ||
| Dannybuell |
great discussion! I think the solid rotor design traps heat on the stator like putting a lid on a pot of boiling water. Scroll down and look at the compufire 3 phase system, it's rotor is slotted. http://www.compufire.com/harley-main.html It looks to me like rotor venting addresses the heat trap shortcoming of a solid rotor. | ||
| Posplayr |
Nuts4mc- you are correct that there is a conductive heat path from the stator to the stator cover and into the engine cases. However, it is not clear how good that path is. It depends on the amount of surface area between the stator and the stator cover. The stator cover usually is gasketed so the primary heat flow will be oil cooling heat removal from the stator cover. If the stator is not getting a lot of oil, not sure the stator cover is going to get a whole lot more. I suspect heat will follow through that path but a direct oil spray will carry away much more heat. It is kinda of like quenching a piece of hot metal in water v.s. trying to have it transfer from one piece of metal to another. Quenching is much more efficient. A sprayer is not hard to do. I don't know what oil pressure you guys run, but I'm running a sprayer with typical 5-10 psi (it varies alot with RPM). I have heard that on the Busa's and GSXR 1K's Suzuki drilled the end of the crankshaft to get an oil jet into the stator area. This is a much more positive approach than trying to scoop up oil from the sump. For one thing the sprayer oil has been cooled down before going to the stator. An oil bath is netter than air, but exchanged oil is best. There may also be some change of state thermodynamics stuff going on. In the reference I posted the oil spray was probably the most efficient in terms of heat removal. (Message edited by posplayr on August 13, 2011) |
