Hybrid Gear-Shift Control During Regeneration to Prevent Oversteer
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Solution Overview
Problem
Conventional hybrid vehicles face challenges in suppressing oversteering while maintaining regeneration efficiency, particularly when rear wheels slip during deceleration, leading to reduced fuel efficiency and instability.
Innovation Solution
The vehicle gear-shifting control apparatus adjusts gear-shifting control and regeneration operation by reducing hydraulic pressure in the friction brake system and increasing input torque during slip states, allowing continuous regeneration without stopping the motor, thereby reducing regenerative braking torque and preventing oversteering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the motor performs a regeneration operation during deceleration, then fuel efficiency is improved, but the rear wheels are apt to fall into a slip state and the vehicle may enter an oversteered state
Solution Approach 1:
The control device changes the gear ratio parameter by performing gear-shifting control (specifically shift-down) to adjust the regenerative braking torque characteristics. This modifies the torque transmission ratio between the motor and rear wheels, allowing the system to maintain regeneration while preventing wheel slip and oversteering
Solution Approach 2:
The system dynamically adjusts the gear ratio in real-time during deceleration by controlling the automatic transmission to perform shift-down operations. This dynamic parameter adjustment allows the regenerative braking torque to be modulated according to vehicle speed and deceleration rate, preventing rear wheel slip while maintaining energy recovery
2Reliability
If the regeneration operation is stopped to resolve the oversteered state, then vehicle stability is improved, but fuel efficiency performance drops
Solution Approach 1:
The control device implements periodic gear-shifting operations (shift-down) during deceleration to cyclically adjust the regenerative braking torque. This periodic adjustment of the transmission gear ratio allows the system to maintain continuous regeneration while preventing the accumulation of excessive torque that would cause oversteering
Solution Approach 2:
By changing the gear ratio parameter through automatic transmission control, the system modifies the relationship between motor rotation speed and vehicle speed. This parameter change allows the regenerative braking torque to be adjusted in real-time, maintaining vehicle stability while continuing energy recovery operations
3Stability of the object's composition
If gear-shifting control is performed during regeneration, then torque shock suppression is improved, but the risk of oversteering increases due to increased torque imparted to rear wheels
Solution Approach 1:
The control device performs preliminary gear-shifting control (shift-down) before the vehicle enters an oversteered state. By anticipating the need for torque adjustment and performing the gear shift in advance, the system suppresses torque shocks while preventing the development of oversteering conditions
Solution Approach 2:
The control device uses feedback from vehicle speed sensors and deceleration rate detection to determine when to perform gear-shifting operations. This feedback control allows the system to adjust the gear ratio in response to actual vehicle conditions, balancing torque shock suppression with oversteering prevention
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 suppresses oversteering and maintains a significant regeneration amount, enhancing fuel efficiency and stability by ensuring the regeneration operation can continue without limiting gear-shifting control.
Implementation Method 1
a motor performs a regeneration operation... a regenerative braking torque is only imparted to the rear wheels
Implementation Method 2
a friction brake system... distributes a braking force to the front wheels and the rear wheels in consideration of the regenerative braking torque
Data Source
Figure 1
Figure 2
Figure 3A
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 an automobile, gear-shifting control of changing a shift stage of the automatic transmission in accordance with the rotation speed of an input shaft and regeneration control of performing regeneration by at least one of distributing a braking force by the friction brake system and imparting a regenerative braking torque to rear wheels by causing the motor to perform a regeneration operation. The controller executes first coordinated gear-shifting control of reducing hydraulic pressure in the friction brake system and changing the shift stage while continuing the regeneration operation of the motor during brake regeneration and executes second coordinated gear-shifting control of changing the shift stage after increasing an AT input torque during non-brake regeneration.