| 摘要 |
<p>A pump of the N, N+1 type has inner and outer lobed rotors designed to provide at the position of deepest mesh a clearance greater than a working clearance over the whole of the tip region to the lobe (10) of the inner rotor, a working clearance being defined at opposite circumferential sides of the said tip region at positions (18, 19) where tangents to the profile at a selected radial section (21) form a first included angle of 20 DEG or more, e.g. 54 DEG . The flanks (13, 14) of the lobe (10) define at each radial section an included angle which reduces to 20 DEG or less, but in any event less than said first included angle.</p> |
