Engine Clutch Control for Electrified Vehicles in Terrain Mode
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Solution Overview
Problem
In electrified vehicles, the engine clutch control methods struggle to effectively engage and disengage in terrain mode, particularly on rough surfaces like mud and sand, leading to battery discharge, synchronization issues, and misrecognition of engine stall due to rapid engine RPM decrease.
Innovation Solution
A method that adjusts engine clutch engagement and disengagement based on engine RPM variation and motor energy usage, using a launch engagement control method to synchronize engine and motor power, and early disengagement control to manage shaft torque and prevent battery exhaustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine clutch is engaged using conventional synchronization control in terrain mode, then the vehicle can operate in HEV mode to improve acceleration, but the motor consumes excessive electrical energy causing battery discharge
Solution Approach 1:
The system performs preliminary assessment of motor energy usage rate and engine RPM variation before engaging the engine clutch. When the motor energy usage rate is high and engine RPM variation is large, the system predicts that synchronization will cause excessive energy consumption, and proactively selects launch engagement control instead, avoiding the energy-wasting synchronization process altogether.
Solution Approach 2:
The control system dynamically switches between synchronization engagement control and launch engagement control based on real-time operating conditions. The engagement control strategy is not fixed but adapts to changing conditions such as motor energy usage rate, engine RPM variation, and driving mode, allowing the system to optimize the balance between acceleration performance and energy consumption.
2Power
If the engine clutch is engaged using synchronization control in terrain mode, then the vehicle can utilize engine power, but the large engine RPM variation makes synchronization difficult to achieve
Solution Approach 1:
The system performs preliminary assessment of engine RPM variation before attempting synchronization. When the variation exceeds a predetermined threshold, the system predicts that synchronization will be difficult or impossible to achieve, and proactively selects launch engagement control instead, avoiding wasted synchronization attempts.
Solution Approach 2:
The system accepts that synchronization may not be achievable under certain conditions and willingly discards the synchronization approach in favor of launch engagement control. Rather than persisting with a doomed synchronization attempt, the system readily switches to an alternative method that works reliably under all conditions.
3Extent of automation
If the engine clutch is disengaged using conventional sequence control in terrain mode, then the control follows a predetermined sequence, but the rapid engine RPM decrease causes misrecognition of engine stall
Solution Approach 1:
The system continuously monitors engine RPM and its rate of change during clutch disengagement. When the RPM decrease rate exceeds a predetermined threshold, the system detects this as a special condition and provides feedback to adjust the disengagement control strategy, preventing misinterpretation of the rapid RPM drop as an engine stall condition.
Solution Approach 2:
The clutch disengagement control is made dynamic rather than purely sequential. The control system adapts the disengagement process based on real-time engine RPM characteristics, adjusting hydraulic pressure reduction rates and timing according to the actual engine state, thereby maintaining reliability under varying operating conditions.
Data Source
AI summary
A method for controlling an engine clutch of an electrified vehicle is provided to easily engage and disengage an engine clutch by applying a launch engagement control method that utilizes power from both of an engine and a motor in accordance with the variation of the number of revolutions per hour of the engine and the usage rate of electrical energy by a motor to engage the engine clutch in a terrain mode and by applying a control method that disengages an engine clutch early in accordance with the number of revolutions per hour of the engine and the shaft torque of the engine clutch in the terrain mode.