Hybrid Vehicle Kick-Down Shift and Clutch Engagement Control
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Solution Overview
Problem
In hybrid vehicles, insufficient control of engine clutch engagement and kick-down shift leads to delayed acceleration response and reduced driving directivity, particularly when transitioning from electric to hybrid modes.
Innovation Solution
A control method and system that determines the order of kick-down shift and engine clutch engagement based on battery discharging power, using sensors to adjust motor and engine speeds, ensuring synchronized engagement and shift operations to maintain acceleration responsiveness and driving directivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If engine clutch engagement and kick-down shift are controlled without determining a specific order, then the control system remains simple, but acceleration response is delayed and driving directivity is reduced
Solution Approach 1:
The controller determines the engagement order of the engine clutch and kick-down shift in advance based on battery discharging power before executing the mode transition. This preliminary determination of control sequence ensures that the components are engaged in the optimal order for rapid acceleration response, rather than using a fixed or arbitrary sequence.
Solution Approach 2:
The control system dynamically adjusts the engagement order of engine clutch and kick-down shift based on real-time battery discharging power conditions. When battery power is sufficient, one engagement sequence is used; when battery power is limited, an alternative sequence is applied. This dynamic adaptation optimizes acceleration response under varying energy availability without requiring a permanently complex control architecture.
2Productivity
If the engine clutch and kick-down shift are engaged simultaneously, then the control process is simplified, but oscillation occurs and acceleration performance deteriorates
Solution Approach 1:
The engagement process is segmented into distinct sequential steps rather than simultaneous action. The controller divides the mode transition into separate phases: first determining the optimal engagement order based on battery power, then executing each engagement (engine clutch or kick-down shift) in the determined sequence. This segmentation prevents oscillation while maintaining efficient acceleration performance.
3Power
If the engine clutch is engaged before kick-down shift, then engine power is immediately available, but motor speed may exceed reference speed causing inefficiency
Solution Approach 1:
The controller continuously monitors motor speed and compares it against reference speed values during the engagement process. Based on this feedback, the controller determines whether to engage the engine clutch first or perform kick-down shift first, ensuring that motor speed remains within efficient operating ranges while still making engine power available when needed.
4Speed
If kick-down shift is performed before engine clutch engagement, then transmission ratio is optimized early, but engine power connection is delayed reducing acceleration
Solution Approach 1:
The controller changes the engagement sequence parameter based on battery discharging power conditions. When battery power is high, kick-down shift is performed first to optimize transmission ratio; when battery power is low, engine clutch engagement is prioritized to ensure power availability. This parameter adjustment resolves the contradiction between transmission optimization and power connection timing.
Data Source
AI summary
A control method of a hybrid vehicle is provided and includes determining whether a current vehicle driving mode is an EV mode, whether a current vehicle driving state satisfies a kick-down shift condition, and whether the current vehicle driving state satisfies a driving mode conversion condition for conversion into an HEV mode. The engine is started when the kick-down shift and the driving mode conversion conditions are satisfied. A current motor speed and discharging power of the battery are measured. The measured motor speed and predetermined motor reference speed are compared based on discharging power of the battery. A transmission input shaft target speed for the kick-down shift is calculated and compared to a predetermined transmission input shaft target reference speed based on discharging power of the battery. A control order is determined based on the comparisons and the kick-down shift and the engagement of the engine clutch are performed.