Torque Control for Transmission Engagements with Road Grade Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electrified vehicles face inefficiencies in transmission engagements due to variations in road grade and vehicle mass, which affect the torque output of electric machines, leading to suboptimal energy conservation and clutch engagement pressures.
Innovation Solution
A method and system that control the torque output of an electric machine based on estimated loads during transmission engagements, including road grade, vehicle mass, driveline losses, and transmission pump loads, by calculating feed-forward and feedback torque compensation values to ensure smooth and efficient engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the electric machine is spun down to conserve energy, then energy conservation is improved, but transmission engagement efficiency deteriorates due to insufficient pump pressure
Solution Approach 1:
The control system applies preliminary action by commanding the electric machine to deliver increased torque output before and during transmission engagement, regardless of whether the input shaft is spinning or stationary. This pre-positioning of torque ensures the transmission pump generates sufficient pressure for smooth clutch engagement, resolving the contradiction between energy conservation and engagement efficiency.
2Productivity
If auxiliary oil pumps are added to generate pressure, then transmission engagement efficiency is improved, but device complexity increases
Solution Approach 1:
The system applies self-service by using the existing electric machine to generate the necessary torque for transmission pump operation, rather than adding auxiliary pumps. The electric machine's torque output is controlled to compensate for road grade and mass variations, enabling the transmission system to self-regulate engagement pressure without additional components, thus improving engagement efficiency while avoiding increased complexity.
3Reliability
If torque output is increased to compensate for road grade and mass variations, then transmission engagement smoothness is improved, but energy consumption increases
Solution Approach 1:
The control system applies dynamics by continuously adjusting the electric machine's torque output based on real-time conditions. The controller determines whether the input shaft is spinning or stationary and dynamically compensates for road grade and mass variations, delivering torque only when necessary for smooth engagement. This dynamic control ensures engagement reliability while minimizing unnecessary energy consumption.
Data Source
AI summary
A method includes 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. Controlling the torque output may include merging a first feed-forward torque with a feedback torque if an input shaft of a transmission gearbox is spinning, or merging a second, different feed-forward torque with the feedback torque if the input shaft is not spinning.