Abstract: The present invention relates to a ring gear and a gear reduction device. The ring gear includes an annular body with a plurality of mounting portions, and a plurality of teeth arranged on an inner circumferential surface of the annular body. The annular body and the teeth are integrally formed from powder metal, and the mounting portions and the teeth are at least partly overlapped in an axial direction of the annular body. The mounting portions are integrally formed with the annular body and the teeth, which results in concentricity between the mounting portion and the teeth being improved and cost of the ring gear being reduced. Furthermore, the mounting portions are overlapped with the teeth, which reduces the axial size of the ring gear.

Abstract: The present invention relates to a ring gear and a gear reduction device. The ring gear includes an annular body with a plurality of mounting portions, and a plurality of teeth arranged on an inner circumferential surface of the annular body. The annular body and the teeth are integrally formed from powder metal, and the mounting portions and the teeth are at least partly overlapped in an axial direction of the annular body. The mounting portions are integrally formed with the annular body and the teeth, which results in concentricity between the mounting portion and the teeth being improved and cost of the ring gear being reduced. Furthermore, the mounting portions are overlapped with the teeth, which reduces the axial size of the ring gear.

Abstract: The present invention provides a ring gear and a gear reduction device. The ring gear includes a one-piece annular body made from powder metallurgy material, and a first ring gear part and a second ring gear part formed on a surface of the annular body. The first ring gear part and the second ring gear part are arranged along an axial direction of the annular body. The ring gear has a density that is less than 92% of its theoretical density and in the range of 6.0 to 8.0 grams per cubic centimeter. The present invention further provides a mold for manufacturing the ring gear. The ring gear of the present invention includes two ring gears integrally formed at once, and the two ring gears have improved concentricity.

Abstract: The present invention relates to a ring gear and a gear reduction device. The ring gear includes an annular body with a plurality of mounting portions, and a plurality of teeth arranged on an inner circumferential surface of the annular body. The annular body and the teeth are integrally formed from powder metal, and the mounting portions and the teeth are at least partly overlapped in an axial direction of the annular body. The mounting portions are integrally formed with the annular body and the teeth, which results in concentricity between the mounting portion and the teeth being improved and cost of the ring gear being reduced. Furthermore, the mounting portions are overlapped with the teeth, which reduces the axial size of the ring gear.

Abstract: The present invention provides a ring gear and a gear reduction device. The ring gear includes a one-piece annular body made from powder metallurgy material, and a first ring gear part and a second ring gear part formed on a surface of the annular body. The first ring gear part and the second ring gear part are arranged along an axial direction of the annular body. The ring gear has a density less than 92% of its theoretical density and a mass of 6.0 to 8.0 grams per cubic millimeter. The present invention further provides a mold for manufacturing the ring gear. The ring gear of the present invention includes two ring gears integrally formed at once, and the two ring gears have improved concentricity.

Abstract: The planetary gear train includes a first sun gear driven by the motor, a first ring gear, a first carrier, and a plurality of first planetary gears arranged at one side of the first carrier and meshing with the first sun gear and the first ring gear. The first sun gear, first planetary gears and first ring gear are helical gears so that meshing surface is increased. Helical teeth formed on an inner surface of the first ring gear mesh with the helical teeth of the first planetary gears. Therefore, the operation is stable and the noise is low. The planetary gears are made of plastic to further decrease the noise. The first ring gear is made by sintered powder metallurgy.

Abstract: The planetary gear train includes a first sun gear driven by the motor, a first ring gear, a first carrier, and a plurality of first planetary gears arranged at one side of the first carrier and meshing with the first sun gear and the first ring gear. The first sun gear, first planetary gears and first ring gear are helical gears so that meshing surface is increased. Helical teeth formed on an inner surface of the first ring gear mesh with the helical teeth of the first planetary gears. Therefore, the operation is stable and the noise is low. The planetary gears are made of plastic to further decrease the noise. The first ring gear is made by sintered powder metallurgy.