Electric axle with space efficient shift assembly
A system and method for an electric axle. The electric axle includes, in one example, a traction motor and an input planetary gear set arranged coaxial to the traction motor. The input planetary gear set includes a sun gear rotationally coupled to the traction motor and a carrier rotationally coupled to a shift sleeve. The electric axle further includes a multi-speed planetary gear set that is arranged coaxial to the input planetary gear set and a shift assembly that includes the shift sleeve positioned axially between the input planetary gear set and the multi-speed planetary gear set.
1 . An electric axle, comprising:
a traction motor; and
an input planetary gear set arranged coaxial to the traction motor and including:
a sun gear rotationally coupled to the traction motor; and
a carrier rotationally coupled to a shift sleeve;
a multi-speed planetary gear set arranged coaxial to the input planetary gear set; and
a shift assembly including the shift sleeve positioned axially between the input planetary gear set and the multi-speed planetary gear set;
wherein the shift assembly is configured to:
in a first positon, rotationally couple the carrier to a sun gear in the multi-speed planetary gear set; and
in a second position, rotationally couple the carrier to a carrier in the multi-speed planetary gear set; and
in a neutral position, rotationally decouple the input planetary gear set from the multi-speed planetary gear set; and
a section of the input planetary gear set carrier rotationally coupled to the shift sleeve; and
a spring positioned below a ball in a recess of the section of the input Planetary gear set carrier;
wherein the ball mates with detents in the shift sleeve;
wherein the detents correspond to the first position, the second position, and the neutral position of the shift assembly;
wherein the shift assembly includes an actuation motor that is mechanically coupled to a shift fork that mates with a recess in the shift sleeve;
wherein the shift assembly includes:
one or more cam gears rotationally coupled to the actuation motor; and
a cam plate positioned vertically below and rotationally coupled to the one or more cam gears;
wherein a shift pin in the shift fork mates with the cam plate.
2 . The electric axle of claim 1 , further comprising a shift fork position sensor coupled to a housing of the electric axle.
3 . The electric axle of claim 1 , wherein:
the input planetary gear set is a simple planetary gear set; and
a ring gear in the input planetary gear set is grounded.
4 . The electric axle of claim 1 , further comprising a differential rotationally coupled to the carrier of the multi-speed planetary gear set.
5 . The electric axle of claim 4 , wherein the differential is arranged coaxial to the input planetary gear set and the multi-speed planetary gear set.
6 . The electric axle of claim 4 , wherein the differential is arranged parallel to and offset from the input planetary gear set and the multi-speed planetary gear set.
7 . The electric axle of claim 1 , wherein a ring gear in the multi-speed planetary gear set is grounded.
8 . An electric beam axle, comprising:
a traction motor; and
an input planetary gear set arranged coaxial to the traction motor and including:
a sun gear rotationally coupled to the traction motor;
a carrier including a section that is rotationally coupled to a shift sleeve;
a multi-speed planetary gear set arranged coaxial to the input planetary gear set;
a shift assembly including the shift sleeve positioned axially between the input planetary gear set and the multi-speed planetary gear set;
a section of the input planetary gear set carrier rotationally coupled to the shift sleeve; and
a spring positioned below a ball in a recess of the section of the input planetary gear set carrier;
wherein the shift assembly is configured to:
in a first positon, rotationally coupled the carrier to a sun gear in the multi-speed planetary gear set;
in a second position, rotationally couple the carrier to a carrier in the multi-speed planetary gear set; and
in a neutral position, rotationally decoupled the input planetary gear set from the multi-speed planetary gear set; and
wherein the input planetary gear set and the multi-speed planetary gear set are simple planetary gear sets;
wherein the ball mates with detents in the shift sleeve;
wherein the detents correspond to the first position, the second position, and the neutral position of the shift assembly;
wherein the shift assembly includes an actuation motor that is mechanically coupled to a shift fork that mates with a recess in the shift sleeve;
wherein the shift assembly includes:
one or more cam gears rotationally coupled to the actuation motor; and
a cam plate positioned vertically below and rotationally coupled to the one or more cam gears;
wherein a shift pin in the shift fork mates with the cam plate.
9 . The electric beam axle of claim 8 , wherein a ring gear in the input planetary gear set and a ring gear in the multi-speed planetary gear set are both grounded.
10 . The electric beam axle of claim 9 , further comprising a differential rotationally coupled to a carrier of the multi-speed planetary gear set.
11 . The electric beam axle of claim 10 , wherein the differential is arranged coaxial to the input planetary gear set and the multi-speed planetary gear set.
12 . The electric beam axle of claim 10 , wherein the differential is arranged parallel to and offset from the input planetary gear set and the multi-speed planetary gear set.
13 . The electric beam axle of claim 10 , wherein the shift assembly includes an actuation motor that is mechanically coupled to a shift fork that mates with a recess in the shift sleeve.