Exhaust Manifold Guide Element Cross-Leakage Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In multi-cylinder combustion engines, the simultaneous opening of exhaust valves leads to cross-leakage, increasing fuel consumption due to high-pressure exhaust gases flowing into lower-pressure branch lines, causing increased pumping work.
Innovation Solution
A guide element is used in the manifold to reduce the cross-section of the common line near the outlet of one branch line, increasing exhaust gas velocity and reducing static pressure, thereby preventing cross-leakage while minimizing flow losses through the use of a hole that reduces relief vortices and redirects gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constrictions are provided in the common line close to the outlets from branch lines, then the risk of cross-leakage is reduced by raising exhaust gas velocity and reducing static pressure, but the flow losses of exhaust gases in the common line increase
Solution Approach 1:
The guide element is divided into multiple functional zones: a first guide surface for gradually reducing cross-section, a hole for pressure equalization, and a second guide surface for flow redirection. This segmentation allows each zone to address specific aspects of the flow control problem, reducing overall flow losses while maintaining cross-leakage prevention.
Solution Approach 2:
The guide element applies different flow control qualities at different locations: the first guide surface creates a gradual constriction with specific curvature radius, the hole provides localized pressure equalization, and the second guide surface directs flow at a specific angle. This local differentiation optimizes flow control while minimizing energy losses.
2Reliability
If the cross-section for exhaust gas flow in the common line is reduced near the outlet aperture, then exhaust gas velocity increases and static pressure decreases, eliminating cross-leakage, but resistance to flow increases
Solution Approach 1:
The first guide surface gradually reduces the cross-section before the exhaust gases reach the critical flow region, allowing the flow to adapt progressively to the constriction. This preliminary action prevents sudden flow separation and reduces turbulence, thereby lowering flow resistance while maintaining the velocity increase needed to prevent cross-leakage.
Solution Approach 2:
The hole in the guide element acts as an intermediary that equalizes pressure between the upstream and downstream sides of the guide element. This pressure equalization reduces the negative pressure effect that would otherwise increase flow resistance, allowing the constriction to maintain its cross-leakage prevention function while minimizing resistance penalties.
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
The solution effectively eliminates cross-leakage and reduces flow losses in the common line, maintaining efficient exhaust gas flow without increasing resistance, thus reducing fuel consumption.
Implementation Method 1
The guide element is provided in the common line upstream of the outlet aperture of the second branch line. The guide element protrudes into the common line so as to cause a reduction of the order of 10-40% in the cross-section for the flow of exhaust gases. The exhaust gases in the common line thus assume an increased velocity and a reduced static pressure close to the outlet aperture from the second branch line into the common line.
Implementation Method 2
The guide element is therefore provided with a hole so that part of the exhaust gases can pass through to the leeside of the guide element. The negative pressure on the leeside of the guide element is thus reduced, with consequent reduction in the magnitude of the relief vortices and hence reduction of the losses of the exhaust gases in the common line when they flow past the guide element.
Data Source
Figure 1~2
Figure 3
AI summary
The present invention relates to a manifold for receiving exhaust gases from a multi-cylinder combustion engine (1). The manifold comprises a common line (4), a first branch line (3a-c) adapted to receiving exhaust gases from a first cylinder (2a-c) and to leading them into the common line (4) via a first outlet aperture (3a1-3c1), and at least one second branch line (3b-d) adapted to receiving exhaust gases from a second cylinder (2b-d) and to leading them into the common line (4) via a second outlet aperture (3b1-3d1) situated downstream of the first outlet aperture with respect to the intended direction of flow of the exhaust gases in the common line (4). The manifold is provided with a guide element (7) which protrudes into the common line (4), thereby reducing the cross-section for the flow of exhaust gases close to the second outlet aperture (3b1-3d1). The guide element (7) has running through it at least one hole (7c), the size of which is such that part of the exhaust gases in the common line (4) which reach the guide surface (7a) passes through said hole (7c). The invention relates also to a combustion engine provided with such a manifold.