| 摘要 |
A positive displacement flowmeter having a pair of non-circular gears in a rolling contact on a pitch line without slippage. The positive displacement flowmeter comprises a casing (3) and a pair of rotors (1, 2) provided in the casing (3) and rotatable around its center axes (4, 5). The pair of rotors (1, 2) have a tooth profile curve which is an oval pitch curve itself having a trajectory of contact points on the pitch line, and they satisfy a condition of r1+r2=K=const r1 d¸1=r2 d¸2, and a moving radius of the oval pitch curve is given by ri=a/ (1-bcosn¸i) (i=1,2), where "ri(i=1, 2)" is the moving radius that is a distance from a center of rotation to the oval pitch curve, "a" is a homothetic coefficient, "b" is a flattening, "n" is a number of lobes, and "¸i(i=1, 2)" is a moving angle.
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