Gear-Shift Control for Rear-Wheel Regeneration During Oversteer
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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 turns leads to decreased lateral force and increased fuel inefficiency.
Innovation Solution
A vehicle gear-shifting control apparatus that reduces the regeneration amount during oversteering, temporarily delays downshifts of the automatic transmission, and maintains regeneration operation to stabilize the vehicle, while preventing torque fluctuations and engine stall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the motor performs a regeneration operation during a turn while decelerating, then fuel efficiency performance is improved, but the lateral force of the rear wheels decreases and the vehicle behavior becomes unstable (oversteered state)
Solution Approach 1:
The controller dynamically adjusts the regeneration amount parameter based on vehicle behavior state. When an oversteered state is detected, the controller reduces the regeneration amount from its maximum value to a lower value, thereby changing the parameter to resolve the contradiction between energy recovery and vehicle stability
Solution Approach 2:
The system transitions from a static regeneration operation to a dynamic one where the regeneration amount can be adjusted in real-time. The controller monitors vehicle behavior and dynamically modifies the regeneration amount during the turn, enabling the system to adapt to changing conditions and maintain stability while recovering energy
2Reliability
If the regeneration operation is stopped to resolve oversteering, then vehicle behavior stability is improved, but fuel efficiency performance decreases
Solution Approach 1:
Instead of completely stopping the regeneration operation (all-or-nothing approach), the controller applies partial action by reducing the regeneration amount to a lower value. This partial reduction is sufficient to resolve the oversteering issue while maintaining some level of energy recovery, thus avoiding the penalty of complete regeneration cessation
3Power
If the automatic transmission performs a downshift during oversteering resolution, then the torque of the rear wheels may fluctuate due to moment of inertia, but the vehicle behavior may become unstable
Solution Approach 1:
The controller anticipates the potential instability caused by downshift during oversteering by implementing preliminary anti-action. When an oversteered state is detected, the controller prohibits downshift operations in advance, preventing the torque fluctuation and behavior instability that would otherwise occur during the gear change
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
The solution effectively stabilizes the vehicle's behavior, maintains regeneration efficiency, and prevents oversteering, thereby improving fuel efficiency and reducing the risk of engine stall.
Implementation Method 1
a motor which generates another travel drive force of the vehicle and which supplies a battery with regenerative energy during deceleration of the vehicle
Implementation Method 2
an automatic transmission of which an input shaft is connected to the engine and the motor and an output shaft is connected to rear wheels and which subjects an input rotation to gear-shifting at a transmission gear ratio corresponding to a selected shift stage and outputs the gear-shifted input rotation
Implementation Method 3
a friction brake system which distributes a braking force to front wheels and the rear wheels in order to realize braking in accordance with a brake pedal operation by a driver
Data Source
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 which executes, during deceleration of a vehicle during which the friction brake system is distributing a braking force to front and rear wheels, a regeneration control of imparting a regenerative braking torque to the rear wheels by causing the motor to perform a regeneration operation and a gear-shifting control of changing a shift stage of the automatic transmission by outputting a gear-shifting signal in accordance with the rotation speed of an input shaft to the automatic transmission. When the controller determines an oversteered state of the vehicle during the regeneration control, the controller increases an input torque of the input shaft so that the regenerative braking torque decreases while maintaining the regeneration operation of the motor and, at the same time, limits the gear-shifting control.