Variable Intake Valve Timing and Lift Control
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Solution Overview
Problem
Existing variable valve systems for internal combustion engines face a trade-off where reducing the working angle of intake valves leads to a decrease in lift amount, resulting in deteriorated intake efficiency and potential misfire or decreased output, and there is a lack of mechanisms that adjust valve characteristics based on engine load.
Innovation Solution
A variable valve device that changes the working angle of intake valves while maintaining constant maximum lift, by adjusting the timing of intake valve closure relative to engine load, and utilizing a tangential and helical port configuration with independent control of intake valves to optimize intake air flow and swirl ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the working angle of the intake valve is reduced, then the valve timing control precision is improved, but the lift amount decreases leading to deteriorated intake efficiency
Solution Approach 1:
The patent segments the valve control functions by introducing separate first and second intake valves with different lift amounts. The first intake valve has a smaller lift amount for precise timing control during low load, while the second intake valve has a larger lift amount for maintaining intake efficiency during high load. This segmentation allows independent optimization of timing precision and intake efficiency without compromise.
Solution Approach 2:
The patent dynamically switches between using the first intake valve and the second intake valve based on engine load conditions. During low load operation, the first intake valve is activated for precise timing control. During high load operation, the second intake valve is activated to maintain sufficient lift amount and intake efficiency. This dynamic adaptation resolves the contradiction between timing precision and intake efficiency across different operating conditions.
2Productivity
If the lift amount of the intake valve is increased, then the intake efficiency is improved, but the valve timing control precision deteriorates
Solution Approach 1:
The patent divides the intake valve system into two segments: a first intake valve with smaller lift amount that provides better timing control precision, and a second intake valve with larger lift amount that provides better intake efficiency. This segmentation allows each valve type to optimize for its specific function without compromise.
Solution Approach 2:
The patent applies local quality by assigning different lift amounts to different intake valves based on their specific operational roles. The first intake valve is designed with smaller lift for precise timing control in specific conditions, while the second intake valve is designed with larger lift for maximum intake efficiency in other conditions. Each valve's local characteristics are optimized for its intended function.
3Device complexity
If a single intake valve is used, then the device complexity is reduced, but the adaptability to different engine load conditions deteriorates
Solution Approach 1:
The patent segments the intake valve system into multiple valves with different characteristics (first intake valve with smaller lift, second intake valve with larger lift). This segmentation enables the system to adapt to different engine load conditions by selecting the appropriate valve, thereby improving versatility while maintaining manageable complexity through modular design.
Solution Approach 2:
The patent introduces dynamic adaptability by enabling switching between different intake valves based on engine load conditions. The system dynamically selects which valve to use - the first intake valve for low load conditions requiring precise timing control, and the second intake valve for high load conditions requiring maximum intake efficiency. This dynamic behavior provides adaptability without requiring a completely complex reconfigurable system.
Data Source
AI summary
A variable valve device for an internal combustion engine is equipped with a variable valve mechanism capable of changing the working angle of an intake valve while holding the maximum lift amount of the intake valve constant. The variable valve device retards the timing for closing the intake valve as the load of the internal combustion engine rises, and enlarges the working angle, while holding the timing for opening the intake valve constant. Operating characteristics of the intake valve are provided in accordance with the load of the internal combustion engine.