Asmo Co., Ltd.

Shinsuke Muroi

Kazunobu Kanno

Tsuyoshi Kuribayashi

Taketo Shimoda

Kouichi Nakamura

Koichi Nakamura

A rotor core includes a plurality of first core sheets and a plurality of second core sheets. The first core sheets and the second core sheets are laminated in the axial direction of the rotor core. Each first core sheet includes a plurality of first teeth laid out in a ring form on a same plane. Each second core sheet includes a plurality of second teeth laid out in a ring form on a same plane. Each first tooth is placed over the associated second tooth in the axial direction of the rotor core. Each tooth has a winding portion extending in the radial direction of the rotor core and an arm portion integrally provided at an outer end of the winding portion in the radial direction of the rotor core and extending in the peripheral direction of the rotor core. Each arm portion has a coupling portion at one end. Each first tooth is coupled to that one of the second teeth which is stacked on another first tooth adjoining in the peripheral direction of the rotor core by coupling of their coupling portions. A portion of each arm portion, which excludes the associated coupling portion, is located further apart from the axis of the rotor core than the associated coupling portion.

Rotor of electric motor and manufacturing method thereof

A plate material is drawn to form a first-drawing product in the shape of an elliptically cylindrical container having an elliptical cross section. Then, the first-drawing product is drawn to form a re-drawing product in the shape of a generally circular cylindrical container. Next, the re-drawing product is drawn to form a late-drawing product in the shape of an elliptically cylindrical container having an elliptical cross section in which a major axis and a minor axis of the elliptical cross section are reversed with respect to a major axis and a minor axis of the elliptical cross section of the first-drawing product. Thereafter, the late-drawing product is drawn to form a final product as a yoke.

Method of manufacturing yoke through multistage-drawing process

In a method of manufacturing a partly flat yoke having curved circumferential walls to which magnets are to be attached and having parallel flat circumferential walls which constitute main magnetic paths and whose each radial thickness is larger than that of the curved circumferential walls, by drawing a sheet of metal plate, the metal plate is held down between a die and projections of a wrinkle preventing plate provided at given angular positions around an outer circumference of a cavity of the die so as to correspond to the curved circumferential walls. Then, a punch presses down the metal plate into the cavity so that material of the metal plate extends axially into the cavity, while the material of the metal plate flows circumferentially from each side of the curved circumferential walls to sides of the parallel flat circumferential walls.

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Hamamatsu, Japan

Shinsuke Muroi