Gear shifting apparatus for multi-speed transmission for electric vehicles
A gear shifting apparatus for a multi-speed transmission for an electric vehicle includes a shifting unit controlling gear shifting by a torque of an actuator, and a parking unit controlling a parking state by the torque of the actuator. In particular, the actuator includes a control motor transmitting a driving torque to a first driven gear and a second driven gear through a drive gear externally gear-meshed with the driven gears, and the shifting unit includes: a shift fork slidably mounted on a fork rail and activating the gear shifting; a profile drum connected to the first driven gear externally engaged with the drive gear, and having a profile groove formed along an exterior circumference of the profile drum; and a shift lug integrally formed with the shift fork and coupled with the profile groove.
1. A gear shifting apparatus for a multi-speed transmission for an electric vehicle, comprising:
a shifting unit configured to control gear shifting by a torque of an actuator; and
a parking unit configured to change a parking state by the torque of the actuator,
wherein the actuator comprises a control motor transmitting a driving torque to driven gears of the shifting unit and the parking unit through a drive gear externally gear-meshed with the driven gears, where the driven gears include a first driven gear and a second driven gear,
wherein the shifting unit comprises:
a shift fork slidably mounted on a fork rail and configured to perform the gear shifting;
a profile drum connected to the first driven gear externally engaged with the drive gear, and having a profile groove formed along an exterior circumference of the profile drum; and
a shift lug integrally formed with the shift fork and coupled with the profile groove, and
wherein the parking unit comprises:
a parking gear;
a parking sprag having an engagement end facing the parking gear and configured to rotate about an axis of a sprag shaft wherein a return spring forces the parking sprag toward a parking release direction;
a parking cam connected to the second driven gear externally engaged with the drive gear, and forming a cam surface on an exterior circumference thereof;
a parking lever rotatably disposed on around a lever shaft, and having an end maintaining contact with the cam surface by another return spring; and
a parking rod connected to a bottom portion of the parking lever and having a cam portion interacting with an end of the parking sprag distal to the sprag shaft.
2. The gear shifting apparatus of claim 1 , wherein a speed reduction is achieved when the torque of the control motor is transmitted from the drive gear to the first and second driven gears.
3. The gear shifting apparatus of claim 2 , wherein a reduction ratio between the drive gear and the second driven gear is less than a reduction ratio between the drive gear and the first driven gear.
4. The gear shifting apparatus of claim 1 , wherein the parking lever rotates at an axis of the lever shaft and thereby horizontally operates the parking rod.
5. The gear shifting apparatus of claim 1 , wherein the cam portion of the parking rod presses the end of the parking sprag to force the engagement end of the sprag to engage with the parking gear.