Mixer Pipe EGR Distribution Uniformity
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Solution Overview
Problem
Existing exhaust gas recirculation (EGR) systems face challenges in achieving uniform EGR distribution to all cylinders, leading to air-fuel ratio and combustion inconsistencies, which result in higher fuel consumption and emissions, particularly in vehicle engines where space and weight constraints limit the use of large surge tanks.
Innovation Solution
The implementation of a mixer pipe positioned within the second exhaust manifold and/or intake passage to mix EGR gases with inlet air, with a specific length that decays higher-order non-uniformities over several engine cycles, ensuring uniform EGR distribution to all cylinders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large surge tank is used to mix exhaust gas with inlet air uniformly, then mixing uniformity is improved, but device complexity and space requirements increase
Solution Approach 1:
The surge tank is divided into multiple smaller mixing chambers or sections, each handling a portion of the exhaust gas flow. This segmentation allows uniform mixing to be achieved through distributed mixing zones rather than requiring a single large tank, reducing overall space requirements while maintaining mixing effectiveness.
Solution Approach 2:
The mixing process is extended along the length of the surge tank by incorporating multiple mixing sections or staged mixing zones. This transforms the mixing from a single-point operation to a distributed process along the flow path, achieving uniformity without requiring excessive tank volume.
2Stability of the object's composition
If a large surge tank is used to achieve uniform EGR distribution, then EGR distribution uniformity is improved, but engine acceleration rate deteriorates
Solution Approach 1:
The surge tank is segmented into multiple smaller mixing chambers that process exhaust gas in parallel. This reduces the total volume required while maintaining uniform EGR distribution, thereby preserving engine acceleration performance by minimizing the inlet volume occupied by the mixing system.
Solution Approach 2:
Instead of using a single large surge tank that provides excessive mixing volume, the system employs multiple smaller mixing sections that provide just sufficient mixing for uniform EGR distribution. This partial action approach achieves the required uniformity without the excessive volume that would harm acceleration.
3Stability of the object's composition
If a large surge tank is used for EGR mixing, then mixing effectiveness is improved, but system weight increases
Solution Approach 1:
The surge tank is divided into multiple smaller mixing chambers, each contributing to the overall mixing effectiveness. The total weight of these smaller chambers is less than a single large tank of equivalent mixing capacity, reducing system weight while maintaining mixing effectiveness through distributed mixing zones.
4Stress or pressure
If donor cylinders route exhaust gas to inlet manifold, then backpressure on non-donor cylinders is reduced, but EGR distribution uniformity deteriorates
Solution Approach 1:
Exhaust gas from donor cylinders is pre-mixed with inlet air in a surge tank before being distributed to the inlet manifold. This preliminary mixing action ensures uniform EGR composition is achieved before distribution, compensating for the pulsing nature of donor cylinder exhaust and maintaining consistent EGR delivery to all cylinders without compromising the backpressure benefits.
Solution Approach 2:
The surge tank acts as an intermediary between the donor cylinders and the inlet manifold. It receives pulsing exhaust gas from donor cylinders, mixes it uniformly with inlet air, and then delivers a stabilized, uniform EGR stream to the inlet manifold, mediating the transition from pulsing to uniform flow while preserving the backpressure advantages.
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 approach reduces EGR percentage variation in the inlet stream to all cylinders, improving engine efficiency and reducing fuel consumption and emissions by ensuring consistent air-fuel ratios across all cylinders.
Implementation Method 1
a mixer pipe positioned within the second exhaust manifold and/or the intake passage to mix exhaust gas recirculation (EGR) gases exhausted by the second cylinder group with inlet air
Data Source
AI summary
An engine system includes a first cylinder group, a second cylinder group, an inlet manifold coupled to the first cylinder group and the second cylinder group, an inlet passage coupled to the inlet manifold to provide inlet air to the inlet manifold, a first exhaust manifold coupled to the first cylinder group, a second exhaust manifold coupled to the second cylinder group, and a mixer pipe positioned within the second exhaust manifold and/or the intake passage to mix exhaust gas recirculation (EGR) gases exhausted by the second cylinder group that are delivered through the second exhaust manifold with inlet air. The mixer pipe forms an inlet end that is coupled to the second exhaust manifold and an outlet end that is located upstream of the cylinders in the first cylinder group and the cylinders in the second cylinder group.