Vehicle system with multi-speed transmission
Methods and systems for a vehicle transmission are provided. A transmission system includes, in one example, an intermediate shaft rotationally coupled to an input shaft and an output shaft, wherein the input shaft is configured to receive rotational input from an electric machine. The system further includes a first gear coupled to the intermediate shaft, and a plurality of clutches coupled to the input shaft and the output shaft and configured to in a first mode, transfer power directly between a second gear coupled to the input shaft, the first gear, and a third gear coupled to the output shaft, and in a second mode, transfer power indirectly between the second gear, the first gear, and/or the third gear.
1. A transmission system, comprising:
an input shaft configured to receive rotational input from an electric motor;
a first gear fixedly coupled to an intermediate shaft that is positioned between the input shaft and an output shaft with regard to an axis that is perpendicular to the rotational axes of the input shaft and the output shaft, wherein the output shaft is coaxial to an axle shaft; and
a plurality of clutches including a first clutch positioned coaxial to the input shaft and a second clutch positioned coaxial to the output shaft, wherein the plurality of clutches are configured to:
in a first mode, transfer mechanical power sequentially between a second gear that is positioned coaxial to the input shaft, the first gear, a third gear arranged coaxial to the output shaft, and the output shaft; and
in a second mode, transfer mechanical power sequentially between the first gear and a fourth gear that is fixedly coupled to the intermediate shaft.
2. The transmission system of claim 1 , wherein the plurality of clutches include a third clutch that is positioned coaxial to the output shaft.
3. The transmission system of claim 2 , wherein the third clutch is a dog clutch.
4. The transmission system of claim 1 , wherein the first clutch is a one-way clutch and the second clutch is a first friction clutch.
5. The transmission system of claim 4 , wherein the third clutch is a second friction clutch.
6. The transmission system of claim 5 , further comprising a lubricant conduit traversing the input shaft and delivering a lubricant to the first friction clutch.
7. The transmission system of claim 6 , wherein the first friction clutch is actuated via a hydrostatic balance piston.
8. The transmission system of claim 1 , wherein the second mode is one of a first gear ratio, a second gear ratio, or a third gear ratio, and the first mode is a fourth gear ratio.
9. The transmission system of claim 1 , wherein the electric motor is a motor-generator.
10. A transmission system in an electric drive axle, comprising:
an input shaft configured to receive rotational input from an electric motor;
a first gear fixedly coupled to the intermediate shaft, a second gear positioned coaxial to the input shaft, and a third gear positioned coaxial to the output shaft;
wherein the intermediate shaft is positioned between the input shaft and the output shaft with regard to an axis that is perpendicular to the rotational axes of the input shaft and the output shaft; and
wherein the output shaft is coaxial to an axle shaft;
a first clutch and a second clutch positioned coaxial to the input shaft;
a third clutch positioned coaxial to the output shaft; and
a controller including executable instructions stored in non-transitory memory that cause the controller to:
operate the first, second, and third clutches in a first mode where mechanical power is transferred sequentially between the first gear, the second gear, and the third gear; and
operate the first, second, and third clutches in a second mode where mechanical power is transferred between the first gear and a fourth gear that is fixedly coupled to the intermediate shaft.
11. The transmission system of claim 10 , wherein the first clutch is a one-way clutch and the second clutch is a friction clutch.
12. The transmission system of claim 11 , further comprising a lubricant conduit traversing the input shaft and providing lubricant to a piston actuator in the friction clutch.
13. The transmission system of claim 10 , wherein the third clutch is a dog clutch.
14. The transmission system of claim 10 , wherein the third clutch is a friction clutch and the transmission system further comprising a one-way clutch coupled to the output shaft.