Interference equation valid for internal gear? 1

[robindbois]

I'm designing and helical gear set made of and internal gear and a small pinion gear. I have an equation to know if there is interference between gears but this was developped for regular spur gear.

To use it for helical gear I just have to use the transversal parameters but I don't know if it still works for internal gears.

N1=number of pinion teeth
N2=number of large gear teeth
p=pressure angle

to avoid interference, equation must be greater or equal to 0:

(N1**2+2*N1*N2)*sin**2(p)-4*N2-4

Robin B

Mech eng
Montréal, Canada

 

[robindbois]

Ok, after a while of playing with the software and good advice from diamondjm I went to that final design:

This is a pair composed of a small pinion and an internal gear: (Fairfield run is available on request)

DP: 48
pressure angle: 20
Helix angle: 30 (right angle)

Pinion: 12 teeth, addendum offset 50%
internal gear: 213 teeth, no offset.

there is no load on the gear and the only concert is noise and vibration.

Any suggestion?