Two-speed coaxial rolling differential with plus-step planet and spur gear stage with stepped ring gear for super duty truck applications
An electric beam axle includes an electric motor, a shiftable reducer, and a rolling differential. The shiftable reducer includes a planetary gearset and the rolling differential includes a compound planetary gearset and a spur gear stage. The electric motor, shiftable reducer and rolling differential are aligned coaxially providing a radially compact electric beam axle.
1. An electric beam axle for a hybrid or electric vehicle, the electric beam axle comprising:
an electric motor;
a rolling differential; and
a shiftable reducer operatively coupled between the electric motor and the rolling differential;
wherein the rolling differential includes a compound planetary gearset and a spur gear stage, a first output of the compound planetary gear set connectable to a first vehicle wheel and a second output of the compound planetary gear set connectable to a second vehicle wheel via the spur gear stage;
wherein the compound planetary gearset comprises:
a sun gear coupled to an output of the shiftable reducer;
a plurality of stepped planet gears positioned radially outwards from the first sun gear with respect to an axis of rotation of the electric beam axle on a planet carrier, each of the plurality of stepped planet gears are configured to mesh with the sun gear; and
a ring gear positioned radially outwards of the plurality of stepped planet gears, wherein each of the plurality of stepped planet gears are coupled with the first ring gear via a secondary planet gear.
2. The electric beam axle of claim 1 , wherein the electric motor, shiftable reducer and rolling differential are coaxially aligned.
3. The electric beam axle of claim 1 , wherein the shiftable reducer includes a planetary gearset.
4. The electric beam axle of claim 1 , wherein each of the plurality of stepped planet gears includes a large planet gear and a small planet gear, wherein the large planet gear is meshed with the sun gear and the small planet gear is meshed with a respective secondary planet gear.
5. The electric beam axle of claim 4 , wherein a carrier shaft of the carrier of the compound planetary gearset is connectable to a first wheel of the axle via a first axle half-shaft and the ring gear of the compound planetary gearset is connectable to a second wheel of the axle via the spur gear stage and a second axle half-shaft.
6. The electric beam axle of claim 3 , wherein the planetary gearset of the shiftable reducer has a first position with a gear ratio of between about 3:1 and 7:1, and a second position with a gear ratio of 1:1.
7. A two-speed shiftable differential comprising:
a shiftable reducer having an input shaft for receiving rotational energy; and
a rolling differential driven by an output of the shiftable reducer;
wherein the rolling differential includes a compound planetary gearset and a spur gear stage, a first output of the compound planetary gearset connectable to a first vehicle wheel and a second output of the compound planetary gear set connectable to a second vehicle wheel via the spur gear stage;
wherein the compound planetary gearset comprises:
a sun gear coupled to an output of the shiftable reducer;
a plurality of stepped planet gears positioned radially outwards from the first sun gear with respect to an axis of rotation of the electric beam axle on a planet carrier, each of the plurality of stepped planet gears are configured to mesh with the sun gear; and
a ring gear positioned radially outwards of the plurality of stepped planet gears, wherein each of the plurality of stepped planet gears are coupled with the first ring gear via a secondary planet gear.
8. The differential of claim 7 , wherein the shiftable reducer and rolling differential are coaxially aligned.
9. The differential of claim 8 , wherein the shiftable reducer includes a planetary gearset.
10. The differential of claim 7 , wherein each of the plurality of stepped planet gears includes a large planet gear and a small planet gear, wherein the large planet gear is meshed with the sun gear and the small planet gear is meshed with a respective secondary planet gear.
11. The differential of claim 10 , wherein a carrier shaft of the carrier of the compound planetary gearset is connectable to a first wheel via a first axle half-shaft and the ring gear of the compound planetary gearset is connectable to a second wheel via the spur gear stage and a second axle half-shaft.
12. The differential of claim 9 , wherein the planetary gearset of the shiftable reducer has a first position with a gear ratio of between about 3:1 and 7:1, and a second position with a gear ratio of 1:1.