External Gear Pump Design

[steamer]

It shouldn't be too hard to compute the OD, width and height from the appropriate equations for Module gears and then just convert them via 25.4, put them in the spreadsheet and "turn the crank"   

Sounds like your far closer to reality with the flow output now.

Sorry I couldn't get into your spreadsheet, but I'm glad Mike did.

Dave

[steamer]

OD of a Module gear

(N+2) x Module = OD

The Pitch diameter for a module gear = Module x N

L is equal to the Pitch diameter + OD of one of the gears

or

L = ((N+2)x Module) + ( Module x N)

and obviously convert to english
....

Dave

[petertha]

Dave, yes I think that's what I have for metric gear formulas. Red are input values on my spreadsheet, black are calculated. I calculate V on the imperial side & convert to ml on metric side, so equation units should match. The screen grab is my approximation to your Porsche pump example using close-ish metric gears. Maybe that's not the right approach but having difficulty seeing why not. V (volume per revolution) is a function of W,D,L (only).

Part of confusion may be the same spreadsheet populated with Mikes engine pump guestimate. But I originally guessed his gear width (W) at 10mm just eyeballing his picture at the time. Your gear is only 2.29mm (0.090"). V is directly proportional to W.

[steamer]

Yes a 10mm long gear is a LOT bigger than 2+mm  LOL   so a lot more

It's the swept volume.   I put a efficiency number in there to try an account for "slip" or oil leaking past the gear teeth and the various seal points...It's a WAG...What it actually is regarding pumping efficiency,  I won't really know, till I actually measure it.

Dave

[steamer]

Well    Mike just dug this up   (  Thanks Mike)

Apparently, Parker Hannifin should be held with a bit of skepticism....

  www.insanehydraulics.com/letstalk/gearpumpdisplacement.html

Apparently  the formula given in their document has a couple of problems.    I'll review it and repost my spreadsheet.

Dave

[petertha]

Yay Mike! How did I not find this link in my internet Googling with very obvious keywords: 'calculate, gear, pump, displacement'. Sheesh I must have 15 technical papers, quasi sales brochures, always missing a critical bit of something... so basically nothing to show for in terms of a functional spreadsheet. Lets hope this sheds some light.