Hybrid Gear Shift and Engine Clutch Sync for Kickdown Acceleration
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Solution Overview
Problem
Hybrid vehicles experience acceleration delay and torque inaccuracy during gear-shifting due to pre-engagement and post-shift methods, leading to suboptimal drivability and control robustness, especially when transitioning from electric vehicle mode to hybrid mode.
Innovation Solution
An engine clutch lock-up control method that synchronizes engine and motor speeds by detecting a kickdown shift, performing simultaneous gear-shifting and clutch engagement, and optimizing torque blending to ensure seamless acceleration and improved drivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pre-engagement and post-shift method is used for gear-shifting, then gear-shifting control is simplified, but acceleration delay occurs and acceleration linearity deteriorates
Solution Approach 1:
The engine clutch is engaged in advance before the gear-shifting operation is completed. The control unit engages the engine clutch during the gear-shifting process rather than waiting for the shift to complete, thereby reducing acceleration delay and improving acceleration linearity while maintaining control simplicity
Solution Approach 2:
The control method dynamically adjusts the engine clutch engagement timing based on the gear-shifting state. The clutch engagement is coordinated with the gear-shifting process through continuous monitoring of shift status and dynamic adjustment of engagement timing, optimizing acceleration performance without increasing system complexity
2Ease of operation
If sequential pre-engagement and post-shift control is used, then control implementation is straightforward, but torque accuracy deteriorates during blending
Solution Approach 1:
The control unit continuously monitors the gear-shifting status and uses this feedback to determine the optimal timing for engine clutch engagement. This feedback mechanism ensures accurate torque blending during the transition from electric vehicle mode to hybrid mode while keeping the control logic straightforward
Solution Approach 2:
The patent replaces complex mechanical coordination with electronic control. The control unit electronically coordinates the engine clutch engagement with gear-shifting through sensor inputs and actuator control, achieving precise torque accuracy without complicating the mechanical system
3Ease of operation
If engine clutch is engaged after gear-shifting completes, then speed synchronization is easier to achieve, but acceleration performance deteriorates
Solution Approach 1:
The engine clutch engagement is performed preliminarily during the gear-shifting process rather than after completion. This preliminary engagement maintains speed synchronization simplicity while significantly improving acceleration performance by reducing the delay between shift initiation and power delivery
Solution Approach 2:
The control method ensures continuous useful action by overlapping the engine clutch engagement with the gear-shifting process. This continuity eliminates idle time during the transition, maintaining both synchronization simplicity and accelerated performance through uninterrupted power transfer preparation
Data Source
AI summary
A control method for controlling gear-shifting and lock-up of an engine clutch in a hybrid vehicle includes: detecting a kickdown shift by a driver while the hybrid vehicle is driving in an electric vehicle mode; starting gear-shifting when the kickdown shift is detected; controlling a difference between an engine speed and a motor speed to be equal to or less than a first reference value; synchronizing the engine speed and the motor speed through an engine speed control; performing torque blending by locking up the engine clutch when the synchronization is completed; and ending the gear-shifting when a target required torque is reached through the torque blending.