Intake Device Branch Passage Asymmetry for Air-Fuel Uniformity
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Solution Overview
Problem
In internal combustion engines, the difference in air-fuel ratios between cylinders is significant due to varying branch passage configurations, especially in Atkinson cycles, leading to inefficiencies and larger intake device sizes when trying to mitigate these differences.
Innovation Solution
The intake device is designed with branch passages arranged in a specific order around a center line to maintain consistent relative positions, ensuring equal influence from blow-back flow across cylinders, and optimized branch passage lengths and shapes to reduce air-fuel ratio disparities without increasing size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the volumes of the branch passages are increased to suppress air-fuel ratio differences, then the air-fuel ratio uniformity improves, but the responsiveness of air intake quantity changes and the intake device size increases
Solution Approach 1:
The patent applies asymmetry by arranging branch passages in a specific asymmetric pattern around the intake chamber. The first branch passage is positioned at a first position, the second branch passage at a second position, and the third branch passage at a third position, where these positions are strategically selected to balance blow-back flow influences without requiring equal branch passage volumes. This asymmetric arrangement allows compact branch passages while maintaining air-fuel ratio uniformity across cylinders.
2Manufacturing precision
If the volumes of the branch passages are increased to suppress air-fuel ratio differences, then the air-fuel ratio uniformity improves, but the intake device size increases
Solution Approach 1:
The patent uses asymmetric positioning of branch passages around the intake chamber to achieve uniform air-fuel ratio distribution without increasing branch passage volumes or overall device size. The specific arrangement of branch passages at different angular positions allows compact design while suppressing blow-back flow effects that cause air-fuel ratio variations.
Solution Approach 2:
The patent transitions from a linear arrangement of branch passages to a radial/dimensional arrangement around the intake chamber. By distributing branch passages in different angular positions (first position, second position, third position) rather than arranging them in a straight line, the patent achieves better flow distribution in a more compact spatial footprint, reducing the overall intake device volume.
3Stability of the object's composition
If the branch passages are arranged symmetrically about a center line, then the relative positions of branch passages are equal, but air-fuel ratio differences still occur due to varying blow-back flow influences
Solution Approach 1:
The patent deliberately breaks the symmetric arrangement of branch passages about a center line. Instead, it positions the first, second, and third branch passages at specific asymmetric positions around the intake chamber. This asymmetric configuration is designed to equalize the influence of blow-back flows from different cylinders on the intake air, thereby achieving uniform air-fuel ratios across all cylinders.
Solution Approach 2:
The patent applies local quality by giving each branch passage a specific position tailored to its cylinder's blow-back characteristics. The first branch passage is positioned at a first position, the second at a second position, and the third at a third position, where each position is optimized for its specific cylinder's operational characteristics rather than treating all branch passages equally through symmetry.
Data Source
AI summary
In an intake device for an internal combustion engine, a difference in the air-fuel ratio between the cylinders is reduced without increasing the lengths of the branch passages. An intake device (23) for an internal combustion engine (1) having at least three cylinders (3) includes: an intake chamber (30) configured to be connected with an air inlet (16); and multiple branch passages (31) connected at upstream ends (41) thereof to the intake chamber and connected at downstream ends thereof to intake ports (6) communicating with the cylinders, respectively, wherein the upstream ends of the branch passages are arranged in a direction of rotation about a predetermined center line X in a same order as an order of ignition of the cylinders.