Pancake Dry Sump Scavengine Pump

[thisispeace]

This is a doodle I've made of a scavenging pump for a dry sump system. The gears mesh such that three scavenging sections use a dedicated idler driven by a single driving gear.

This design is intended to be driven by an extension of a camshaft or an intermediate gear, such as one between a crank and cam gear.

The gears are 1.025" deep, 8 teeth @ 4 pitch making for a nice PD of 2.000.

http://docs.google.com/File?id=dggnckr6_13679jsh8gs_b
http://docs.google.com/File?id=dggnckr6_137d24qs4g8_b
http://docs.google.com/File?id=dggnckr6_138kc9hjzdf_b

[thisispeace]

This is a doodle I've made of a scavenging pump for a dry sump system. The gears mesh such that three scavenging sections use a dedicated idler driven by a single driving gear.

This design is intended to be driven by an extension of a camshaft or an intermediate gear, such as one between a crank and cam gear.

The gears are 1.025" deep, 8 teeth @ 4 pitch making for a nice PD of 2.000.

http://docs.google.com/File?id=dggnckr6_13679jsh8gs_b
http://docs.google.com/File?id=dggnckr6_137d24qs4g8_b
http://docs.google.com/File?id=dggnckr6_138kc9hjzdf_b

[Drew Price]

You may want to consider an o-ringed seal around the perimeter of the side plates, so you don't have to rely on scraping and re-sealing with Ultra Black or whatever every time you take it apart, esp. since the first time you have to take apart you're liable to not have a flat side plate anymore!

Is it just the scooping action of the teeth to push oil into the radial passages?

Do you think you'll have to have it mounted down low or horizontal so it doesn't have to suction prime itself? If it's mounted up high on a camshaft it might not be able to make enough suction to start drawing oil through, especially up and around into the top passage.

Maybe you will have issues with oil 'leaking' from the pressure to the feed sides between passages around the drive gear too, not sure though.

This sort of configuration (for me) makes more sense to drive with an aux. electric motor, so you can mount the housing down really low amd horizontally (like a pancake!) alongside the oil pan, then it doesn't have to self prime on startup, it's already primed, and just has to suck out the oil pan.

Also, dowel the side plates into the case, with hollow dowels and a throughbolt, or dedicated dowels, to locate the shafts for the gears, or you will never get all 4 gears centered in their bores, and I imagine the housing will be AL, and it will get chewed up from the required tight tolerances overlapping from the slop in the bolt holes.

If you dowel it, make sure to machine some prying notches into the housing at intervals so you can work the cover off straight.

Do not let freshmen dissassemble it.

Also, you might consided only having a cover on one side. Just leave a (thin) solid wall on one side, so you just have to blind machine it, it'll be a lot easier to clamp that way too. And only have to make one cover. And then you can cut one side of the gear shafts on the CNC centered in the bores without taking the fixture out of the machine.

Best,
Drew

[MalcolmG]

very interesting idea, I assume you've posted here hoping for some feedback

The first thought that came to mind was that it might be a bit tricky to package nicely: you're going to literally have AN fittings coming off it on all sides, with an inlet and outlet on each. The plumbing could be a real nightmare - I'd consider some sort of internal galleries to combine all your outlets into a single fitting and perhaps to bring all your fittings onto a single side. I would imagine this being done through one of the outer plates, probably by making it thick enough that it can be drilled for galleries from the sides, then hammer oversized ball bearings in to close up the ends of the holes.

[Nihal]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">then hammer oversized ball bearings in to close up the ends of the holes </div></BLOCKQUOTE>

These might be a more elegant solution to plugging the passages.

http://sherex.thomasnet-naviga...pe=1&keyword=550-050 (http://sherex.thomasnet-navigator.com/keyword/all-categories?&key=all&keycateg=100&keyprod=&SchType=1&keyword=550-050)

[VFR750R]

Looks fairly inefficient for a scavenge pump overall. I'd never want anything but dual or tri-lobe rotors anyways unless you have to use available gears. Much more swept volume per width and shaft centerline!

I agree with the sentiment that your plumbing needs cleaning up. I too suggest a thicker end plate with passages milled into it. Internal plumbing is almost always cheaper and more reliable in the end.

My latest idea has been to build an internal dry sump. Most 600cc cases have room for a 3-4 stage dry sump near the water pump shaft, and then run direct or through a chain. Makes it easy to not worry about the pump and associated fittings leaking. You'll have one line out to the tank, and one back in.
With even more work and dedication, one could segment the crankcase from the transmission and use the transmission side as the 'tank'. Or attach the tank directly to the cases somehow so that there were no external lines!

[thisispeace]

Thanks for the input, everyone.

If you want the Solidworks files to play with, I put them online at:

http://web.ics.purdue.edu/~bmunden/pancake_pump.rar (http://web.ics.purdue.edu/%7Ebmunden/pancake_pump.rar)

[thisispeace]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Drew Price:
Is it just the scooping action of the teeth to push oil into the radial passages?

Do you think you'll have to have it mounted down low or horizontal so it doesn't have to suction prime itself? </div></BLOCKQUOTE>

Drew,

It's a positive displacement pump, so the reduction in volume as the teeth mesh will push the interstitial fluid along it's way, unless there is enough back pressure to stall the driving torque.

Positive displacement pumps self-prime pretty well, regardless of orientation.

Good machine tips too. I put a back skin on the pump to get rid of one plate. Then I got lazy and didn't do the dowels, o-ring groove, or internal plumbing http://fsae.com/groupee_common/emoticons/icon_smile.gif.

Best,

Brandon Munden

[thisispeace]

Also, here's a gerotor pump section that can be stacked and staged into an external or internal pump.

IGS file:

web.ics.purdue.edu/~bmunden/pump_section.IGS

http://web.ics.purdue.edu/~bmunden/pump_section