Torque Control Mode Transition in Hybrid Vehicle Creep
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Solution Overview
Problem
Hybrid vehicles experience undesirable vehicle motion during transitions from speed control mode to torque control mode in creep mode due to uneven torque supply from the torque source, leading to driveline inefficiencies and component degradation.
Innovation Solution
Adjusting the torque output of the electric machine or engine in response to a virtual torque converter impeller speed when the torque converter clutch is locked, allowing for smoother transitions between speed control and torque control modes by maintaining torque converter impeller torque and reducing driveline disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the torque source transitions from speed control mode to torque control mode during creep mode, then driveline efficiency is improved, but undesirable vehicle motion occurs due to uneven torque supply
Solution Approach 1:
The system performs preliminary actions by calculating a virtual torque converter impeller speed and determining the torque converter impeller torque before the actual mode transition occurs. This allows the control system to pre-compute the necessary torque adjustments and smoothly transition from speed control to torque control mode without causing driveline disturbances or undesirable vehicle motion.
2Loss of energy
If the torque source transitions from speed control mode to torque control mode, then driveline efficiency is improved, but driveline torque disturbances occur
Solution Approach 1:
The system uses feedback by continuously monitoring the virtual torque converter impeller speed and using it to calculate the torque converter impeller torque. This feedback mechanism allows the control system to adjust the torque source output in real-time during the transition, maintaining torque stability and preventing driveline torque disturbances while improving driveline efficiency.
3Loss of energy
If the torque source transitions from speed control mode to torque control mode, then driveline efficiency is improved, but degradation of driveline components occurs
Solution Approach 1:
The control system performs preliminary calculations of the virtual torque converter impeller speed and torque converter impeller torque before the mode transition. This allows the system to pre-adjust torque levels and avoid sudden torque changes that could cause mechanical shocks and degradation of driveline components such as the torque converter clutch, transmission elements, and connected mechanical parts.
Data Source
AI summary
Systems and methods for transitioning a torque source between speed control and torque control modes during a vehicle creep mode are disclosed. In one example, torque of an electric machine is adjusted in response to a torque converter model. The torque converter model provides for a locked or unlocked torque converter clutch.