Continuously Variable Valve Lift Control for Engine Starting
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Solution Overview
Problem
Traditional gasoline engines suffer from inefficiencies due to machining tolerances and component deformations in continuously variable valve lift mechanisms, leading to deviations in valve lift consistency and reduced engine performance, especially at low temperatures.
Innovation Solution
A control strategy for a continuously variable valve lift mechanism that uses eccentric wheels with different profiles for two valves per cylinder, allowing self-learning to determine the current position and adjust lift positions based on temperature and engine conditions, ensuring optimal valve lift regulation for improved starting and combustion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a continuously variable valve lift mechanism is implemented, then engine efficiency is improved, but valve lift consistency deteriorates due to machining tolerances and component deformations
Solution Approach 1:
The patent implements a self-learning control method where the control unit detects the actual valve lift positions using sensors, compares them with target positions, and automatically adjusts the eccentric shaft positions to compensate for deviations caused by machining tolerances and component deformations. This closed-loop feedback system eliminates the need for high-precision manufacturing while maintaining consistent valve lift performance.
Solution Approach 2:
The system performs automatic self-adjustment without requiring manual calibration or intervention. The control unit autonomously learns the actual positions of valve lift components during engine operation and compensates for deviations, enabling the system to self-correct manufacturing inaccuracies and maintain optimal performance.
2Manufacturing precision
If valve lift positions are adjusted to compensate for manufacturing deviations, then valve lift consistency is improved, but system complexity increases
Solution Approach 1:
The control unit integrates multiple functions including position detection, data processing, deviation calculation, and actuation control within a single device. The eccentric shaft mechanism simultaneously serves as both the valve lift adjustment mechanism and the position sensor reference, reducing the need for separate calibration components and simplifying the overall system architecture.
3Reliability
If self-learning control is implemented, then low-temperature starting is improved, but detection and measurement difficulty increases
Solution Approach 1:
The patent introduces intermediate swing arms as mechanical intermediaries that translate the eccentric shaft rotation into precise valve lift movements. These mechanical intermediaries provide inherent position reference through their geometry and motion constraints, reducing the complexity of direct position detection while improving control reliability during cold starting.
Data Source
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AI summary
A control strategy for a continuously variable valve lift mechanism, an apparatus and a nonvolatile computer storage medium are disclosed. The control strategy includes: after an engine is energized, the continuously variable valve lift mechanism self learning to determine a current position; if the self learning is successful, the continuously variable valve lift mechanism being located at a maximum lift position, preparing for starting the engine, and determining a regulating mode based on a starting temperature, wherein at the time of normal temperature start, regulation is performed from the maximum lift position to a minimum lift position, and at the time of low temperature start, regulation is performed from the maximum lift position to a position where the two valves for the same cylinder have a maximum lift difference; if the self learning fails, entering a preliminary start mode; entering a CVVL control mode based on an operation condition of the engine; and powering off the engine.