Exhaust Manifold Riser Geometry for Multi-Cylinder Engines
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Solution Overview
Problem
In multi-cylinder internal combustion engines, it is challenging to manage the simultaneous exhaust flow from multiple cylinders without causing overlapping valve opening times, leading to increased pressure and fuel consumption due to the difficulty in directing high-pressure exhausts away from lower-pressure exhausts in the manifold, resulting in inefficient exhaust ejection.
Innovation Solution
The design of a manifold with a riser featuring strategically positioned areas with varying geometry, specifically a successively reduced cross-sectional area and wedge-shaped portions, to facilitate the flow of exhausts in the predetermined direction, reducing flow resistance and preventing high-pressure exhausts from mixing with lower-pressure exhausts, thereby optimizing the exhaust ejection process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If exhausts from multiple cylinders are led into the manifold simultaneously, then the manifold can handle the exhaust flow from all cylinders, but high-pressure exhausts may penetrate into branch lines with lower-pressure exhausts causing increased pressure and fuel consumption
Solution Approach 1:
The riser is segmented into multiple inlet openings positioned at different locations, with each inlet opening receiving exhausts from specific cylinders. This segmentation allows simultaneous reception of exhausts from multiple cylinders while preventing high-pressure exhausts from penetrating into branch lines with lower-pressure exhausts through strategic positioning and geometry design.
Solution Approach 2:
Different areas of the riser are given different geometries tailored to the specific exhaust flow characteristics from each cylinder. The riser includes areas with successively reduced cross-sectional areas and wedge-shaped portions at specific inlet openings to optimize the flow direction and prevent harmful penetration, while other areas maintain constant cross-sectional areas.
2Stress or pressure
If constrictions are added to the riser to increase exhaust speed and reduce static pressure, then lower-pressure exhausts can be ejected into the riser, but exhaust flow losses in the riser increase significantly
Solution Approach 1:
Instead of adding constrictions at all outlets, the invention applies geometric modifications only at specific inlet openings where simultaneous exhaust reception occurs. The riser includes areas with successively reduced cross-sectional areas and wedge-shaped portions at selected locations, while other areas maintain constant cross-sectional areas, thereby preventing harmful penetration without causing significant exhaust flow losses throughout the entire riser.
3Productivity
If the riser is equipped with areas with different geometries at all inlet openings, then simultaneous exhaust reception is facilitated, but flow resistance to the exhausts in the manifold increases significantly
Solution Approach 1:
The riser is segmented into different types of areas: inlet openings with geometric modifications (successively reduced cross-sectional areas and wedge-shaped portions) for simultaneous exhaust reception, and other inlet openings with constant cross-sectional areas. This segmentation allows the manifold to facilitate simultaneous exhaust reception where needed while maintaining low flow resistance in other areas.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively reduces the flow resistance and prevents high-pressure exhausts from entering the wrong flow direction, allowing for efficient simultaneous exhaust ejection from multiple cylinders without increasing the engine's work, thus minimizing fuel consumption.
Implementation Method 1
the flow passage in said area has a successively reduced cross sectional area at an outlet end in relation to at an inlet end of said area... the exhausts in the riser obtain an increased speed and a reduced static pressure
Implementation Method 2
the riser comprises a wall construction that comprises an internal wall surface defining the flow passage through said area... a wedge-shaped portion, comprising a first wall surface with a gradient, such that it reduces the cross sectional area of the flow passage in the riser, and a subsequent second wall surface with a gradient, such that it expands the flow passage's cross sectional area
Data Source
Figure 1
Figure 2~3
AI summary
The present invention relates to a manifold for receiving exhausts from a multi- cylindrical internal combustion engine (1). The internal combustion engine (1) has such a firing order that the riser (4a, 4b) in the manifold (4a, 4b) receives exhausts from two cylinders (c2, c4, c7, c8) during an overlapping stage, simultaneously via an inlet opening (3a2, 3b3) arranged upstream and from an inlet opening (3a4, 3b4) arranged downstream in the riser (4a, 4b). The riser (4a, 4b) comprises a substantially constant cross sectional area, except in one area (A, B), which is located in a position in connection with the inlet opening arranged downstream (3a4, 3b4) of the two inlet openings (3a2, 3a4, 3b3, 3b4), receiving exhausts simultaneously. Said area (A, B) has a geometry facilitating receipt and flow of exhausts in the predetermined direction in the riser (4a, 4b), on occasions when the two inlet openings (3a2, 3a4, 3b3, 3b4) receive exhausts simultaneously.