Oval Corporation

Seigo Ono

Katsuichi Uchida

Flowmeter with a pair of helical gears using an oval pitch curve as a reference rack tooth profile. The tooth height ratio of the reference rack tooth profile is &#x3c0;/4. The reference rack tooth profile is an oval pitch curve of two or less leaves. The moving radius of the oval pitch curve is expressed by &#x3c1;=a/(1&#x2212;b cos n&#x3b8;), where &#x3c1; is a moving radius which is a distance between the center of rotation and the oval pitch curve, 'a' is a similarity factor, 'b' is a degree of flatness, n (n&#x2266;2) is the number of leaves, and &#x3b8; is an argument. The tooth height ratio is h=a/(1&#x2212;b)&#x2212;g, where gis a distance between poles of the oval pitch curve and pitch line, wherein g=a cos &#x3b8;/(1&#x2212;b cos n&#x3b8;). Values for the similarity factor &#x201c;a&#x201d;, degree of flatness &#x201c;b&#x201d;, and distance gare determined so that the tooth height ratio may be &#x3c0;m/4.

Positive displacement flowmeter and helical gear

A position 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 and a pair of rotors provided in the casing and rotatable around its center axes. The pair of rotors, 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 rrK=const rd&#x3b8;=rd&#x3b8;, and a moving radius of the oval pitch curve is given by ri=a/(1&#x2212;b cos n&#x3b8;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, &#x201c;b&#x201d; is a flattening, &#x201c;n&#x201d; is a number of lobes, and &#x201c;&#x3b8;i (i=1, 2) is a moving angle.

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Shinjyuku-ku, Japan

Seigo Ono