Variable Event Angle Mechanism for Dual Intake Valve Engine
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Solution Overview
Problem
Existing internal combustion engines face challenges in enhancing cylinder flow and ensuring combustion stability, particularly in low-load ranges, due to limited intake air flow and variable valve control configurations.
Innovation Solution
A variable event angle mechanism is implemented in a dual-intake valve engine, where one intake valve is driven by a rocker cam and the other by a rotary cam, allowing for adjustable lift characteristics and event angles to optimize intake air flow, enhancing combustion stability and efficiency across various load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single valve variable control is used with both intake valves opening at top dead center, then the valve timing control is simplified, but the flow inside the cylinder cannot be enhanced sufficiently in low-load range
Solution Approach 1:
The patent divides the dual intake valves into two groups: one valve (first intake valve) with fixed opening timing at top dead center, and another valve (second intake valve) with variable opening timing. This segmentation allows independent control of each valve's timing, enabling optimized air flow in low-load conditions while maintaining simple control for the first valve.
Solution Approach 2:
The patent implements dynamic control where the opening timing of the second intake valve is variable based on operating conditions, while the first intake valve maintains a fixed timing. This dynamic adjustment of the second valve's opening timing allows the system to adapt to low-load conditions and enhance cylinder flow when needed.
2Device complexity
If only lift amount difference between valves is used to enhance flow, then the valve mechanism remains simple, but combustion stability cannot be ensured in low-load range
Solution Approach 1:
The patent introduces dynamic timing control for the second intake valve, allowing its opening timing to be adjusted based on operating conditions. This dynamic timing adjustment, combined with lift amount control, provides sufficient control authority to ensure combustion stability in low-load conditions without significantly complicating the valve mechanism.
Solution Approach 2:
The patent changes the operating parameters of the second intake valve by varying its opening timing in addition to lift amount. This parameter change enables better control over cylinder filling and combustion stability in low-load conditions while maintaining a relatively simple valve mechanism structure.
3Productivity
If dual-intake valve configuration is used, then the potential for enhanced flow exists, but the benefit is not realized in low-load range with small intake amount
Solution Approach 1:
The patent implements dynamic control of the second intake valve's opening timing to optimize air flow in low-load conditions. By adjusting the timing when intake amount is small, the system maximizes the benefit of having dual intake valves, creating favorable flow patterns and enhancing cylinder filling efficiency even when total intake air amount is limited.
Solution Approach 2:
The patent optimizes the operating parameters of the dual intake valves by setting the first valve to open at top dead center and allowing variable timing for the second valve. This parameter optimization enables the dual-valve configuration to deliver enhanced flow performance across the entire operating range, including low-load conditions with small intake amounts.
Data Source
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AI summary
Provided is an internal combustion engine including two intake valves for each cylinder, the internal combustion engine including: a fixed cam for driving one of the two intake valves with a lift characteristic having a valve opening timing close to a top dead center; a variable valve actuation mechanism capable of changing, in accordance with an engine running condition, lift characteristics between a low-lift characteristic having an event angle and a lift amount each being smaller than an event angle and a lift amount of the fixed cam, and a high-lift characteristic having the event angle and the lift amount each being larger than the event angle and the lift amount of the fixed cam; and a variable cam for driving another of the two intake valves, the variable cam including the variable valve actuation mechanism, in which the variable valve actuation mechanism is configured to set the lift characteristic of the variable cam so as to obtain a valve opening timing on a retard side relative to the valve opening timing of the fixed cam in a case of the low-lift characteristic.