Patent ID: 9297433
Filing Date: 2016-03-29
CPC Classification: F16D,F16H

Claim Text:
1. An electric parking brake driving device for driving a parking brake actuator which generates a braking force and applies the braking force to a vehicle wheel by converting a rotational movement from a rotating member into a translatory movement, transmitting the converted translatory movement to a piston and by pushing a disc rotated together with the vehicle wheel by a brake pad biased by the piston, the electric parking brake driving device comprising: an electric motor; and a reduction gear mechanism for transmitting a driving force of the electric motor to the rotating member, wherein the reduction gear mechanism includes: a gear body; a drive gear provided in the gear body and fixed to an output shaft of the electric motor; a first rotating shaft rotatably supported on the gear body through a first bearing portion provided on the gear body; a first driven gear formed on the first rotating shaft and having a plurality of gear teeth more than a number of gear teeth formed on the drive gear, whereby the first driven gear engages with the drive gear; a transmitting gear formed on the first rotating shaft and integrally rotating with the first driven gear; a second rotating shaft rotatably supported on the gear body through a second bearing portion provided on the gear body, the second rotating shaft being rotatable about an axis which extends in an axial direction; a second driven gear formed on the second rotating shaft and having a plurality of gear teeth more than a number of gear teeth formed on the transmitting gear, whereby the second driven gear engages with the transmitting gear; a sun gear provided on the second rotating shaft and integrally rotating with the second driven gear; a plurality of planetary gears engaged with the sun gear and orbiting around an outer periphery of the sun gear in response to the rotation of the sun gear; a ring gear disposed around the planetary gears and engaging therewith at an inner peripheral surface, the ring gear being non-rotatable by engaging with the gear body; and a carrier member connecting the plurality of planetary gears and at the same time connected to the rotating member to be rotated by the orbiting of the planetary gears, whereby a rotation of the sun gear is outputted to the rotating member through a reduction, wherein the second bearing portion includes a pair of second bearing members, the gear body includes a supporting wall which is formed integrally with an outer wall of the gear body and extends from the outer wall towards a rotation center of the second rotating shaft to separate the planetary gears from the second driven gear, the supporting wall being disposed between the second driven gear and the planetary gears relative to the axial direction, one of the pair of second bearing members is disposed on the supporting wall to support the second rotating shaft at one side of the second driven gear, and an other of the pair of second bearing members is disposed on the gear body to support the second rotating shaft at an other side of the second driven gear opposite to the one side of the second driven gear relative to the axial direction.