Sumitomo Electric Sintered Alloy, Ltd.

Sumitomo Electric Industries, Limited

Honda Motor Co., Ltd.

Toshiyuki Kosuge

Masato Uozumi

Keizo Harada

Koichi Sogabe

Kenichi Watanabe

Heisuke Kobayashi

Shinichi Hirono

Reiko Okuno

Shinya Kurihara

Katsuhiko Yazama

[Means for Solution] A gear member includes a tooth having a tooth flank whose profile is an involute curve, wherein in a cross-section of the tooth perpendicular to a face width direction, the tooth has a depression, near a top land, hollowed in the tooth flank relative to the involute curve.

Gear member

In an internal gear pump, a diameter of a base circle is set to A mm, a radius of a rolling circle is set to b mm, a diameter of a locus circle is set to C mm, and an amount of eccentricity is set to e mm. A trochoidal curve T is drawn by rolling the rolling circle along the base circle without slipping and by using a locus of a fixed point distant from a center of the rolling circle by e. A tooth profile of an inner rotorhaving n teeth is formed based on an envelope of a group of the locus circles each having a center on the trochoidal curve T. A pump rotoris formed by combining the inner rotor with an outer rotor having (n+1) teeth. A tooth-profile curve of the inner rotor satisfies the following expression (1). Because K&#x3c;1 is satisfied, cusps s are not formed at opposite edges of each addendum of the inner rotor. 

Internal gear pump

An internal gear pump includes an inner rotor having n teeth and an outer rotor having (n+1) teeth. A tooth profile of the inner rotor is an envelope of a group of locus circles () each having a diameter C and having a center on a trochoidal curve (T), the trochoidal curve being drawn along a locus of a fixation point, which is located distant from a center of a rolling circle () by e, when the rolling circle () rolls along a base circle () without sliding. A tooth profile of the outer rotor is an envelope of a group of tooth-profile curves of a formation inner rotor, the envelope being obtained by first drawing the formation inner rotor in which a diameter of the locus circle () is equal to C' determined from expression (C&#x2212;t), revolving a center (O) of the formation inner rotor by one lap along a circle (S) having a diameter (2e) and centered on a center (O) of the outer rotor, and rotating the formation inner rotor 1/n times during the revolution.

An oil pump that can be reduced in weight and is excellent in wear resistance and easy to manufacture is provided. The oil pump includes an oil pump housing formed of aluminum alloy, and an inner rotor and an outer rotor that slide along the oil pump housing with contact kept therebetween to suck and discharge oil. Composite layers including porous metallic bodies are arranged at parts of the oil pump housing that contact the inner rotor and the outer rotor. Pores of the porous metallic bodies are impregnated with the aluminum alloy constituting the oil pump housing.

Oil pump

An internal gear pump which improves the mechanical efficiency and the life and reduces noises by eliminating non-uniformity of the gaps between teeth. In the internal gear pump wherein the tooth spaces of the outer gear and the tooth tips of the inner gear form an epicycloid and the tooth tips of the outer gear and the tooth spaces of the inner gear form a hypocycloid, these cycloids are formed by four circles that roll on the pitch circle of each gear such that the gap between teeth in a region where the outer and inner gears mesh most deeply with each other is substantially equal to the gap between teeth in a region where the depth of mesh between the outer and inner gears are the shallowest.

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Itami, Japan

Toshiyuki Kosuge