Hybrid Shift-Down Torque Control for Oversteer During Regeneration
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Solution Overview
Problem
Conventional hybrid vehicles fail to simultaneously suppress oversteering and maintain regeneration efficiency in rear wheel-drive vehicles, as the regeneration operation during deceleration reduces lateral force on rear wheels, leading to oversteering, and stopping regeneration to correct this worsens fuel efficiency.
Innovation Solution
The controller adjusts the input torque of the automatic transmission's input shaft during regeneration and shift-down, increasing it in oversteered states to reduce regenerative braking torque while maintaining the regeneration operation, thereby stabilizing the vehicle and maintaining fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the motor performs a regeneration operation during deceleration in a rear wheel-drive vehicle, then fuel efficiency is improved, but the lateral force of the rear wheels decreases causing the vehicle to fall into an oversteered state
Solution Approach 1:
The controller dynamically adjusts the regenerative braking torque parameter based on vehicle state detection. When an oversteered state is detected during regeneration control, the controller reduces the regenerative braking torque to restore lateral force on rear wheels, thereby maintaining vehicle stability while still preserving some regeneration operation to sustain fuel efficiency benefits
Solution Approach 2:
The system implements feedback control by continuously monitoring vehicle behavior and detecting oversteered states. When oversteering is detected during regeneration, the controller provides feedback to adjust the regenerative braking torque downward, and when the oversteered state resolves, the controller increases the torque again, creating a closed-loop control system that balances stability and energy recovery
2Stability of the object's composition
If the regeneration operation is stopped to resolve the oversteered state, then the lateral force of the rear wheels recovers and oversteering is suppressed, but fuel efficiency performance drops
Solution Approach 1:
Instead of completely stopping the regeneration operation, the controller applies partial action by reducing the regenerative braking torque to a lower level that is sufficient to resolve the oversteered state while maintaining some degree of regeneration operation. This partial reduction in torque allows the system to achieve stability correction without fully sacrificing fuel efficiency benefits
3Adaptability or versatility
If the automatic transmission performs a shift-down when the vehicle is in an oversteered state, then the transmission can adapt to deceleration conditions, but the torque fluctuation may further destabilize the vehicle behavior
Solution Approach 1:
The controller performs preliminary anti-action by detecting the oversteered state before the shift-down operation and preemptively adjusting the input torque to counteract the destabilizing effect. By increasing the input torque in advance of the shift-down event, the system prepares to offset the torque fluctuation that will occur during the transmission shift, thereby preventing further destabilization
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively stabilizes the vehicle's behavior by reducing torque fluctuations during shift-downs and maintaining regeneration efficiency, preventing oversteering while ensuring optimal fuel performance.
Implementation Method 1
a motor 5 which generates a travel drive force of the automobile 1 and which supplies a high-voltage battery 9 with regenerative energy during deceleration of the automobile 1
Implementation Method 2
an automatic transmission 8 of which an input shaft 8a is connected to the engine 4 and the motor 5 and an output shaft 8b is connected to rear wheels 2R and which subjects an input rotation to gear-shifting at a transmission gear ratio corresponding to a selected shift stage
Data Source
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AI summary
A vehicle gear-shifting control apparatus is equipped with an engine, a motor, an automatic transmission, a friction brake system, and a controller. The controller increases an input torque of an input shaft according to a shift-down so that an acceleration fluctuation of the vehicle which accompanies the shift-down equals a target acceleration fluctuation, and when the controller determines an oversteered state during regeneration control and during a shift-down, the controller increases the input torque of the input shaft so that a regenerative braking torque decreases while maintaining a regeneration operation of the motor and the controller causes the automatic transmission to perform the shift-down in a state where an amount of increase of the input torque of the input shaft in accordance with the shift-down has been increased as compared to during a non-determination of an oversteered state.