Vehicle system and method for controlling torque delivery during transmission engagements with road grade and mass estimation
A method according to an exemplary aspect of the present disclosure includes, among other things, controlling a torque output of an electric machine of an electrified vehicle based on estimated loads present during a transmission engagement of the electrified vehicle.
1. A method, comprising:
controlling a torque output of an electric machine of an electrified vehicle based on estimated loads present during a transmission engagement of the electrified vehicle, the controlling step is performed each time a shift device is moved from a neutral gear to a drive gear, and wherein the estimated loads are based on at least a road grade estimate, a vehicle mass estimate, driveline loads, and transmission pump loads.
2. The method as recited in claim 1 , wherein the controlling step includes determining whether an input shaft of a transmission gearbox is spinning or stationary as the transmission engagement is initiated.
3. The method as recited in claim 1 , wherein the estimated loads are based on an amount of inertia necessary to spin up an input shaft of a transmission gearbox.
4. The method as recited in claim 1 , wherein the controlling step includes:
estimating the loads present during the transmission engagement; and
adjusting the torque output of the electric machine to compensate for the estimated loads.
5. The method as recited in claim 1 , wherein the controlling step includes:
determining the road grade estimate; and
deriving a first torque compensation value from the road grade estimate.
6. The method as recited in claim 5 , wherein the controlling step includes:
determining the vehicle mass estimate; and
deriving a second torque compensation value from the vehicle mass estimate.
7. The method as recited in claim 6 , comprising deriving a third torque compensation value from the driveline loads and a fourth torque compensation value from the transmission pump loads.
8. The method as recited in claim 7 , comprising determining a feed-forward torque by adding the first torque compensation value, the second torque compensation value, the third torque compensation value and the fourth torque compensation value.
9. The method as recited in claim 8 , wherein the controlling step includes modifying the torque output based on the feed-forward torque and a feedback torque.
10. The method as recited in claim 7 , comprising deriving a fifth torque compensation value based on an amount of inertia required to spin up an input shaft of a transmission gearbox.
11. The method as recited in claim 10 , comprising determining a feed-forward torque by adding the first torque compensation value, the second torque compensation value, the third torque compensation value, the fourth torque compensation value, and the fifth torque compensation value.
12. The method as recited in claim 11 , wherein the controlling step includes modifying the torque output based on the feed-forward torque and a feedback torque.
13. The method as recited in claim 1 , wherein the electrified vehicle is a modular hybrid transmission (MHT) vehicle.
14. A vehicle system, comprising:
a transmission gearbox;
an electric machine that supplies torque to an input shaft of said transmission gearbox;
a torque converter disposed between said electric machine and said transmission gearbox; and
a control unit in communication with said electric machine and configured to modify a torque output of said electric machine to compensate for variations in road grade and vehicle mass during a transmission engagement.
15. The vehicle system as recited in claim 14 , comprising a transmission pump pressurized by said electric machine.
16. The vehicle system as recited in claim 14 , wherein said control unit is configured to estimate loads present during said transmission engagement and compensate for said estimated loads by modifying said torque output.
17. The vehicle system as recited in claim 14 , comprising a shift device that actuates said transmission engagement when moved from a neutral gear to a drive gear.
18. The vehicle system as recited in claim 14 , wherein said control unit is configured to modify said torque output to additionally compensate for variations in driveline loads and transmission pump loads during the transmission engagement.