Planetary gear device and vehicle wheel drive device

A planetary gear device comprising an internal gear, a planetary gear engaging with the internal gear, a sun gear positioned at the center of the internal gear and engaging with the planetary gear, a planetary carrier rotatably supporting the planetary gear in a state in which the planetary gear engages with the internal gear and the sun gear, a bearing inner cylinder comprising the internal gear on an inner circumferential surface, a bearing coaxially fitting in the outer circumference of the bearing inner cylinder, an output shaft outer cylinder coaxially fitting in the outer circumference of the bearing, and an output shaft end plate that fixes the planetary carrier and is supported by the output shaft outer cylinder, wherein a drive shaft, disposed on a first direction side of one of the axial direction of the bearing inner cylinder, is coupled to the sun gear, and the planetary carrier is arranged on a second direction side of the other of the axial direction of the bearing inner cylinder, the planetary gear device comprising:

• an annular slinger fitted in the drive shaft coupled to the sun gear on the first direction side of the planetary gear device;
• an annular drive shaft seal plate fitted in an inner circumference of the bearing inner cylinder on the first direction side of the bearing inner cylinder, the drive shaft being inserted in the annular drive shaft seal plate, and the annular drive shaft seal plate arranged apart from the slinger so as to form a gap in the radial direction between the drive shaft and the slinger;
• and
• an annular carrier seal plate fitted in the inner circumference of the bearing inner cylinder, the planetary carrier being inserted at the center of the annular carrier seal plate so as to form a gap in the radial direction between the planetary carrier and the annular carrier seal plate, on the second direction side of the planetary gear device,
• wherein:
• a drive shaft side annular protrusion protruding over the circumference of the drive shaft is formed on one of the slinger and the drive shaft seal plate, a drive shaft side annular groove recessed over the circumference of the drive shaft is formed on the other of the slinger and the drive shaft seal plate, and a first labyrinth seal comprises the drive shaft side annular protrusion and the drive shaft side annular groove;
• and
• a carrier side annular protrusion protruding over the circumference of the shaft of the planetary carrier is formed on one of the carrier seal plate and the planetary carrier, a carrier side annular groove recessed over the circumference of the shaft of the planetary carrier is formed on the other of the carrier seal plate and the planetary carrier, and a second labyrinth seal comprises the carrier side annular protrusion and the carrier side annular groove.