Hybrid Vehicle Transmission Control for Pre-Stop Gearshift Stability
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Solution Overview
Problem
In hybrid vehicles with automatic transmissions, pre-stop gearshifts involving significant reverse torque can cause input shaft reversal, leading to abnormal operations and potential damage due to clutch sliding and improper oil supply, resulting in unstable drivability and transmission failure.
Innovation Solution
A method of controlling the hybrid vehicle that includes pre-gearshift, mid-gearshift, and post-gearshift controls to gradually reduce and then increase the reverse torque of the motor generator during regenerative braking, ensuring smooth and stable gearshift by managing torque levels and hydraulic pressure to prevent input shaft reversal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative braking is performed with significant reverse torque in the motor generator, then electricity is generated to charge the battery, but the input shaft of the automatic transmission reverses causing abnormal operations and potential damage
Solution Approach 1:
The control system dynamically adjusts the reverse torque of the motor generator in three distinct phases (pre-gearshift, mid-gearshift, post-gearshift) depending on the gearshift state. During pre-gearshift control, reverse torque is reduced to a first level; during mid-gearshift control, it is further reduced to a second level; and during post-gearshift control, it is increased back to normal. This dynamic torque management prevents input shaft reversal while maintaining regenerative braking functionality.
Solution Approach 2:
The invention changes the torque parameter of the motor generator based on the gearshift progression. By monitoring the gearshift state and adjusting the reverse torque magnitude accordingly, the system optimizes the balance between energy recovery and transmission protection. The torque parameter is modified from high (during regenerative braking) to low (during gearshift) and back to high (after gearshift completion).
2Productivity
If pre-stop gearshift is performed with considerable reverse torque, then regenerative braking efficiency is improved, but clutch components slide and friction members may be damaged
Solution Approach 1:
The control system performs preliminary action by reducing the reverse torque to a first level before the actual gearshift occurs (pre-gearshift control phase). This preparatory torque reduction prevents excessive stress on clutch components during the upcoming gearshift, while still maintaining some regenerative braking function. The brake system compensates for the reduced motor generator torque to maintain overall braking performance.
3Use of energy by moving object
If reverse torque is maintained at high level during gearshift, then energy recovery is maximized, but oil pump operates in reverse causing improper oil supply
Solution Approach 1:
The control system acts as an intermediary by introducing a mid-gearshift control phase where reverse torque is reduced to a second level (lower than the first level) during the actual gearshift process. This intermediate torque level prevents the oil pump from operating in reverse while still allowing some energy recovery. The brake system serves as another intermediary to compensate for the reduced motor generator contribution to braking force.
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 method prevents abnormal operations and damage to the automatic transmission by stabilizing pre-stop gearshifts, ensuring smooth and stable gear changes while maintaining the integrity of the transmission components.
Implementation Method 1
A hybrid vehicle has a regenerative braking function that provides not only braking force but electricity to charge a battery by generating a predetermined amount of reverse torque in a motor generator in braking
Implementation Method 2
a step of pre-gearshift control that reduces reverse torque of a motor generator to the level of a first step, when a pre-stop gearshift order is generated in regenerative braking
Implementation Method 3
a step of mid-gearshift control that reduces the reverse torque of the motor generator to the level of a second step, which is smaller than the level of the first step, from a point of time where the actual gearshift starts to be performed by the gearshift order to a point of time where engaging components of an automatic transmission are completely interlocked
Data Source
AI summary
A method of controlling a hybrid vehicle including an automatic transmission and a motor generator comprises a pre-gearshift control, a mid-gearshift control, and a post-gearshift control. It is possible to prevent abnormal operations and damage of an automatic transmission due to reverse rotation of the input shaft of the automatic transmission and achieve smooth and stable pre-stop gearshift, by appropriately controlling reverse torque exerted in the input shaft of the automatic transmission, when a vehicle equipped with a hybrid driving apparatus including the automatic transmission performs the pre-stop gearshift.