Hybrid Vehicle Transmission Torque Compensation for Shifting Delay
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Solution Overview
Problem
Hybrid electric vehicles experience gear shifting delay and odd acceleration feelings during power-off upshifts due to positive input torque and limited charging torque, which hinder smooth gear shifting and cause discomfort.
Innovation Solution
A method for controlling the transmission by applying a compensation value to the engine torque based on motor speed, under-charging-limit available motor torque, and engine operation point during part load operations, ensuring the sum of engine and motor torque becomes negative during shift phases, thereby synchronizing input side speed with the target gear position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative brake control is applied to charge the battery with a large portion of engine torque during power-off upshift, then battery charging efficiency is improved, but gear shifting delay occurs due to positive input torque preventing smooth speed synchronization
Solution Approach 1:
The patent dynamically adjusts the regenerative brake torque based on the shifting phase. During the speed synchronization phase, the regenerative brake torque is controlled to be smaller than in other phases, allowing the input side speed to synchronize smoothly with the target gear position. This dynamic adjustment resolves the contradiction by temporarily reducing battery charging efficiency to achieve smooth gear shifting, then maximizing charging efficiency during other phases.
2Use of energy by moving object
If engine torque is maintained at optimal operation point during part load operation, then fuel efficiency is improved, but input torque becomes positive causing odd acceleration feeling and shifting delay
Solution Approach 1:
The patent applies preliminary anti-action by controlling the engine torque to be smaller than the optimal operation point torque during the speed synchronization phase. This preemptive reduction in engine torque prevents the positive input torque condition that causes odd acceleration feelings and shifting delay. By anticipating the shifting requirement and adjusting torque beforehand, the system maintains fuel efficiency while ensuring smooth gear shifting.
3Reliability
If regenerative torque is limited by charging power capacity, then battery protection is improved, but transmission input torque remains positive causing gear shifting delay
Solution Approach 1:
The patent implements dynamic control of regenerative brake torque based on shifting phase detection. During the speed synchronization phase, the system temporarily reduces the regenerative brake torque below the maximum charging capacity, allowing the transmission input torque to become negative and enabling smooth speed synchronization. This dynamic adjustment resolves the contradiction by temporarily prioritizing gear shifting speed over maximum battery charging, then maximizing charging efficiency during other phases while maintaining battery protection.
Data Source
AI summary
In a hybrid electric vehicle, gear shifting delay and odd feeling when shifting gears, due to the accelerator pedal being depressed after an upshift being determined according to a release of the pedal, may be prevented. A method for controlling a transmission of the hybrid electric vehicle, includes determining a gear shifting type when a predetermined gear shifting condition is satisfied; determining an engine operation mode when the gear shifting type is power-off upshift; determining, when the engine operation mode is a predetermined mode according to an air-fuel ratio condition, a compensation value according to at least one of a motor speed, an under-charging-limit available motor torque, and an engine operation point in the predetermined mode; and applying the compensation value to an engine torque.