Planetary gear device

A planetary gear device comprising:

• a sun gear having a row of external teeth;
• a plurality of planetary gears disposed around the sun gear, each of the plurality of planetary gears having a row of external teeth which mesh with the external teeth of the sun gear;
• a planetary carrier at which the plurality of planetary gears are rotatably provided, the planetary carrier being rotatable around the sun gear together with the plurality of planetary gears;
• and
• a ring gear having a pair of rows of internal teeth which mesh with the external teeth of the plurality of planetary gears, the plurality of planetary gears being arranged inward of the ring gear,
• wherein the planetary carrier includes an oil feeding passage which feeds lubricating oil to at least one of the plurality of planetary gears,
• wherein the ring gear is a double helical gear in which the pair of rows of internal teeth are arranged in a direction of an axis line of the ring gear and the internal teeth of one of the rows and the internal teeth of the other of the rows are inclined in different directions, the ring gear including at least one discharge passage,
• wherein the at least one discharge passage includes an inlet-side portion and an outlet-side portion, the inlet-side portion being closer to an inlet configured to open in a region between the pair of rows of internal teeth at an inner peripheral surface of the ring gear, and the outlet-side portion being closer to an outlet configured to open in a region of an outer peripheral surface of the ring gear, and
• wherein the inlet-side portion is formed at the ring gear so that the inlet-side portion is inclined in a forward rotation direction of the planetary carrier, with respect to a reference line extending in a radial direction of the ring gear.