Vehicle Torque Control During Transmission Upshifts
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Solution Overview
Problem
Automated vehicle transmissions face challenges in maintaining smooth acceleration during gearshifts, particularly upshifts, due to torque variations and response times of engine actuators, leading to potential instability and poor driveability.
Innovation Solution
A control system that determines a torque demand signal based on transmission speed and driver demand signals, using a torque ratio value to compensate for torque losses during gearshifts, and applies modifications to the torque demand signal to ensure a smooth and refined power output, while accounting for the response times of engine actuators and drivetrain characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If driveability filters are tuned to smooth torque demand heavily to maintain driveability, then vibration and drivetrain instability are reduced, but the vehicle response becomes unresponsive and refinement during gearshifts is lost
Solution Approach 1:
The control system performs preliminary action by detecting the gearshift state in advance and proactively adjusting the torque demand signal before the torque hole occurs. The system determines when a gearshift is in progress based on transmission output speed and torque ratio changes, then modifies the torque demand accordingly to prevent rather than react to instability.
Solution Approach 2:
The system changes parameters dynamically by adjusting the torque demand signal based on the detected gearshift state. When a gearshift is detected, the system modifies the torque demand parameter to compensate for the upcoming torque drop, using variable adjustment rather than fixed filtering to maintain both stability and responsiveness.
2Power
If engine torque is increased during an upshift to compensate for torque losses, then power output is maintained, but a lag arises between the initial torque drop and the compensation effect creating a torque hole
Solution Approach 1:
The control system applies preliminary action by detecting the gearshift state and adjusting the torque demand signal before the torque hole occurs. The system determines when a gearshift is in progress based on transmission output speed and torque ratio changes, then proactively modifies the torque demand to compensate for the upcoming torque drop rather than reacting after the drop occurs.
Solution Approach 2:
The system provides beforehand cushioning by preparing the torque demand signal in advance to offset the expected torque drop during gearshift. The control system calculates the required compensation based on the detected gearshift state and applies it to the torque demand signal before the actual torque hole occurs, cushioning against the adverse effect in advance.
3Stability of the object's composition
If driveability filters remove torque compensation during gearshifts, then smooth acceleration is maintained, but the refinement and power delivery during upshifts are degraded
Solution Approach 1:
The control system performs preliminary action by detecting the gearshift state in advance and proactively adjusting the torque demand signal before the torque hole occurs. The system determines when a gearshift is in progress based on transmission output speed and torque ratio changes, then modifies the torque demand accordingly to prevent rather than react to instability.
Solution Approach 2:
The system uses feedback by continuously monitoring transmission output speed and torque ratio to detect gearshift state. This feedback information is used to dynamically adjust the torque demand signal, creating a closed-loop control that adapts to the actual gearshift conditions and maintains both smoothness and refinement.
Data Source
AI summary
A control system (32, 33) for a vehicle (10), the control system (32, 33) comprising one or more controllers, the control system (32, 33) being configured to: receive a transmission speed signal that is indicative of an output speed of a transmission (24) of the vehicle (10) as the transmission (24) performs a gearshift; receive a driver demand signal that is indicative of a driver demand for acceleration of the vehicle (10) during the gearshift; and determine a torque demand signal for an engine (20) of the vehicle (10) in accordance with the transmission speed signal and the driver demand signal.