Two speed gear reducer for electric drive module
An electric drive module (EDM) for an electrified vehicle includes an electric motor and a two-speed gearbox including: a housing; a first planetary gearset (PG) having a first sun gear coupled to the electric motor; a second compound PG having a second sun gear coupled to the first PG; a third PG having a third sun gear coupled to the second PG and a third planetary carrier coupled to an output of the gearbox. A first torque transfer device (TTD) selectively couples a second ring gear of the second PG to the housing; and a second TTD selectively couples a first ring gear of the first PG to the housing. The gearbox is selectively switchable among (i) a first gear where the first TTD is engaged and the second TTD is disengaged; and (ii) a second gear where the second TTD is engaged and the first TTD is disengaged.
1 . An electric drive module (EDM) for an electrified vehicle, the EDM having an electric motor and a two-speed gearbox assembly, the two-speed gearbox assembly comprising:
a housing;
a first planetary gearset including a first sun gear, a first ring gear and a first planetary carrier, wherein the first sun gear is coupled to an output of the electric motor;
a second compound planetary gearset including a second sun gear, a second ring gear and a second compound planetary carrier, wherein the second sun gear is directly coupled to the first carrier;
a third planetary gearset including a third sun gear, a third ring gear and a third planetary carrier, wherein the third sun gear is directly coupled to the second sun gear, and wherein the third planetary carrier is coupled to an output of the two-speed gearbox assembly;
a first torque transfer device that selectively couples the second ring gear to the housing; and
a second torque transfer device that selectively couples the first ring gear to the housing;
wherein the gearbox assembly is selectively switchable among (i) a first gear where the first torque transfer device is engaged grounding the second ring gear to the housing, and the second torque transfer device is disengaged; and (ii) a second gear where the second torque transfer device is engaged grounding the first ring gear to the housing, and the first torque transfer device is disengaged.
2 . The EDM of claim 1 , wherein the second compound planetary carrier is directly coupled to the first ring gear and the third ring gear is fixed to the housing.
3 . The EDM of claim 1 , wherein the output of the two-speed gearbox assembly is coupled to a planetary differential.
4 . The EDM of claim 3 , wherein the planetary differential comprises a compound planetary differential having a fourth sun gear, a fourth ring gear and a fourth carrier carrying compound planetary gearsets;
wherein the fourth ring gear is coupled for common rotation with the output of the two-speed gearbox assembly; and
wherein the sun gear is coupled to one half shaft axle and the fourth carrier is coupled to the other half shaft axle.
5 . The EDM of claim 1 , wherein first gear comprises a first torque multiplication and second gear comprises a second torque multiplication; and
wherein the first torque multiplication is greater than the second torque multiplication.
6 . The EDM of claim 1 , wherein the first and second torque transfer devices comprise friction clutches.
7 . The EDM of claim 1 , wherein the first and second torque transfer devices comprise dog clutches.
8 . The EDM of claim 1 , wherein the first and second torque transfer devices comprise brakes.
9 . The EDM of claim 1 , wherein the EDM comprises only one electric motor.
10 . The EDM of claim 1 , wherein the two-speed gearbox assembly comprises only three planetary gearsets consisting of the first and third planetary gearsets and the second compound planetary gearset.
11 . The EDM of claim 10 , wherein the first and third planetary gearsets comprise simple planetary gearsets.
12 . The vehicle of claim 11 , wherein the first torque transfer device comprises a selectable one-way clutch (SOWC).
13 . The EDM of claim 1 , further comprising a park lock gear coupled to the two-speed gearbox assembly upstream of differential and downstream of the torque transfer devices.
14 . An electrified vehicle, comprising:
an electric drive module (EDM) including:
a housing;
an electric motor; and
a two-speed gearbox assembly comprising:
a first planetary gearset including a first sun gear, a first ring gear and a first planetary carrier, wherein the first sun gear is coupled to an output of the electric motor;
a second compound planetary gearset including a second sun gear, a second ring gear and a second compound planetary carrier, wherein the second sun gear is directly coupled to the first carrier;
a third planetary gearset including a third sun gear, a third ring gear and a third planetary carrier, wherein the third sun gear is directly coupled to the second sun gear, and wherein the third planetary carrier is coupled to an output of the two-speed gearbox assembly;
a first torque transfer device that selectively couples the second ring gear to the housing; and
a second torque transfer device that selectively couples the first ring gear to the housing;
wherein the gearbox assembly is selectively switchable among (i) a first gear where the first torque transfer device is engaged grounding the second ring gear to the housing, and the second torque transfer device is disengaged; and (ii) a second gear where the second torque transfer device is engaged grounding the first ring gear to the housing, and the first torque transfer device is disengaged.
15 . The electrified vehicle of claim 14 , wherein the second compound planetary carrier is directly coupled to the first ring gear and the third ring gear is fixed to the housing, and
wherein the output of the two-speed gearbox assembly is coupled to a planetary differential.
16 . The electrified vehicle of claim 15 , wherein the planetary differential comprises a compound planetary differential having a fourth sun gear, a fourth ring gear and a fourth carrier carrying compound planetary gearsets;
wherein the fourth ring gear is coupled for common rotation with the output of the two-speed gearbox assembly; and
wherein the sun gear is coupled to one half shaft axle and the fourth carrier is coupled to the other half shaft axle.
17 . The electrified vehicle of claim 14 , wherein first gear comprises a first torque multiplication and second gear comprises a second torque multiplication; and
wherein the first torque multiplication is greater than the second torque multiplication.
18 . The electrified vehicle of claim 14 , wherein the first torque transfer device comprises a first brake and the second torque transfer device comprises a second brake.
19 . The electrified vehicle of claim 14 , wherein the two-speed gearbox assembly comprises only three planetary gearsets consisting of the first and third planetary gearsets and the second compound planetary gearset;
wherein the first and third planetary gearsets comprise simple planetary gearsets; and
wherein the EDM comprises only one electric motor.
20 . The electrified vehicle of claim 15 , further comprising a park lock gear coupled to the two-speed gearbox assembly upstream of the differential and downstream of the torque transfer devices.