Internal Combustion Engine Intake Port Volume Ratio Optimization
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Solution Overview
Problem
Internal combustion engines face challenges in improving output performance and exhaust gas emission performance due to reverse flow of combustion gas into the intake system, which complicates the valve train system and increases costs.
Innovation Solution
An internal combustion engine design with a simplified valve train system that uses a fixed valve timing type valve train, where the intake port volume ratio is optimized within specific ranges of intake valve overlap amounts to suppress reverse flow, allowing for improved combustion and emission performance without the need for variable valve timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a variable valve train is employed to reduce valve overlap period at low rotational speed, then emission performance is improved, but device complexity increases and manufacturing cost increases
Solution Approach 1:
The patent extracts the variable valve timing mechanism from the system and replaces it with a fixed valve train design. By setting the valve overlap period to a specific range (6° to 16° crank angle) and controlling the intake port volume ratio (0.45 ≤ Rv < 0.75), the system eliminates the need for complex variable valve timing mechanisms while achieving acceptable emission performance through optimized fixed geometry parameters.
2Object-generated harmful factors
If a variable valve train is employed to vary valve lift amounts or timings, then combustion performance is improved, but manufacturing cost increases
Solution Approach 1:
The patent changes the geometric parameters of the intake port system to achieve optimal combustion performance. By controlling the intake port volume ratio Rv within the range 0.45 ≤ Rv < 0.75 and setting the valve overlap period to 6° to 16° crank angle, the design optimizes gas flow and combustion characteristics without requiring expensive variable valve timing mechanisms, thereby maintaining ease of manufacture.
3Power
If valve overlap period is prolonged to improve output performance, then power output increases, but reverse flow of combustion gas into intake port increases
Solution Approach 1:
The patent optimizes the valve overlap period parameter to a specific range (6° to 16° crank angle) that balances output performance and reverse flow prevention. This optimized overlap period, combined with controlled intake port volume ratio, allows sufficient time for gas exchange to maintain power output while limiting the duration and intensity of reverse flow into the intake port.
4Object-generated harmful factors
If valve overlap period is reduced to prevent reverse flow, then emission performance is improved, but output performance deteriorates
Solution Approach 1:
The patent identifies and implements an optimal parameter range for valve overlap period (6° to 16° crank angle) that achieves a balance between emission performance and output performance. By controlling the intake port volume ratio within 0.45 ≤ Rv < 0.75, the design ensures that the reduced overlap period does not excessively limit gas exchange, thereby maintaining acceptable power output while improving emission characteristics.
5Object-generated harmful factors
If intake port volume ratio is reduced to suppress reverse flow, then emission performance is improved, but intake air amount decreases
Solution Approach 1:
The patent controls the intake port volume ratio Rv within the range 0.45 ≤ Rv < 0.75 to achieve optimal balance between reverse flow suppression and intake air amount. This parameter optimization ensures sufficient intake air for combustion while limiting the volume available for reverse flow of exhaust gases into the intake port, thereby improving emission performance without excessively reducing air intake.
Data Source
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AI summary
An internal combustion engine is configured to satisfy the relation expressed by 0 < Rv < 0.000438 × θ2 - 0.0407 × θ + 1.55 in a range of an intake valve overlap amount θ(°) from 20° to 45°, where Rv denotes an intake port volume ratio obtained by dividing an intake port internal volume Vp by a cylinder stroke volume Vc, and the intake valve overlap amount θ(°) is a crank angle from an intake valve opening timing when the intake valve (20) starts opening to an intake top dead center of the piston (10). The engine improves output performance as well as both combustion performance and emission performance by suppressing reverse flow of the combustion gas into the intake system.