Powertrain Neutral Idle Torque Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing vehicle control systems face challenges in efficiently transitioning from a neutral idle state to a drive state, particularly in managing engine torque and clutch energy to balance acceleration and heat generation during gear engagement, leading to potential overheating or inadequate acceleration.
Innovation Solution
A method of controlling a vehicle powertrain by disengaging a shift element to enter a neutral idle state, then incrementally increasing torque capacity based on accelerator pedal position, with an offset adjustment based on clutch energy to optimize engine torque during re-engagement, ensuring balanced acceleration and heat management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If engine torque is increased during transition from neutral idle to engaged state, then acceleration performance is improved, but heat generation in the shift element increases leading to potential overheating
Solution Approach 1:
The controller prepares for the transition by disengaging the shift element in advance before the actual gear change is needed. This preliminary disengagement allows the system to be ready for quick re-engagement when acceleration is required, while managing the torque application to prevent excessive heat generation during the brief engagement period
Solution Approach 2:
The system dynamically adjusts the torque capacity of the shift element during the transition from neutral idle to engaged state. The controller modulates the torque capacity based on real-time conditions, increasing it gradually to achieve smooth acceleration while preventing sudden torque spikes that would cause excessive heat generation in the shift element
2Speed
If the shift element is held engaged continuously, then acceleration response is improved, but fuel efficiency deteriorates during stationary periods
Solution Approach 1:
The system dynamically switches between two states: during stationary periods, the shift element is disengaged to reduce engine load and improve fuel efficiency; when acceleration is required, the shift element is quickly re-engaged to provide immediate acceleration response. This dynamic state switching allows the system to optimize for either fuel efficiency or acceleration response depending on the current operating condition
Solution Approach 2:
The controller implements periodic engagement and disengagement of the shift element based on driving conditions. During periods when the vehicle is stationary or cruising, the shift element remains disengaged to save fuel. When acceleration is detected or required, the shift element is engaged periodically to provide the necessary acceleration, creating a rhythm of engagement that balances fuel efficiency with acceleration performance
Data Source
AI summary
To reduce fuel consumption, a transmission is shifted into a neutral state, called neutral idle, when a vehicle stops in a drive mode. During a transition from a neutral idle state to an engaged state, the engine torque is controlled to avoid excessive shift energy and to mitigate acceleration drop. Specifically, the engine torque is set to a level equal to a sum of a transmission torque capacity and an offset, which is a function of accelerator pedal position. The transmission torque capacity is calculated based on the engaging shift element torque capacity and torque ratios associated with the kinematics and the torque converter. To accommodate noise factors such as variation over time, the offset function is adapted in response to measured clutch energy and acceleration drop.