Internal Combustion Engine EGR Delivery Uniformity
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Solution Overview
Problem
Conventional internal combustion engines with a dedicated EGR cylinder do not uniformly deliver EGR volumes to working cylinders, leading to uneven combustion performance across a range of operating conditions.
Innovation Solution
Implementing a configuration where two adjacent cylinders operate on a two-stroke combustion cycle as dedicated EGR cylinders, with an EGR supply conduit extending between their exhaust ports and the intake ports of four-stroke cylinders, ensuring more uniform delivery of recirculated exhaust gas for improved combustion stability and reduced NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If one cylinder is used as dedicated EGR source in a four-cylinder engine, then EGR production is simplified, but EGR delivery uniformity deteriorates
Solution Approach 1:
The engine is segmented into two functional groups: two cylinders operating on a two-stroke cycle as dedicated EGR sources, and two cylinders operating on a four-stroke cycle as working cylinders. This segmentation allows the EGR function to be distributed across multiple cylinders rather than concentrated in one, improving delivery uniformity while maintaining system simplicity.
Solution Approach 2:
Different cylinders are assigned different operational characteristics: the dedicated EGR cylinders operate on a two-stroke cycle with customized air-fuel ratios optimized for EGR production, while the working cylinders operate on a four-stroke cycle for normal combustion. This local differentiation ensures each cylinder performs its specific function optimally.
2Device complexity
If a single dedicated EGR cylinder is used, then system simplicity is maintained, but combustion performance uniformity deteriorates
Solution Approach 1:
The combustion system is segmented into two operational modes: two-stroke cycle for EGR cylinder and four-stroke cycle for working cylinders. This segmentation enables independent optimization of each mode and ensures uniform combustion performance across all cylinders by distributing EGR production across multiple sources.
Solution Approach 2:
The system dynamically switches between two-stroke and four-stroke operational modes based on the specific cylinder being operated. This dynamic adaptation allows the engine to optimize performance for each cylinder's specific function, improving overall combustion performance uniformity and reliability.
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 configuration achieves more uniform EGR distribution, enhancing combustion stability, reducing NOx emissions, and allowing for optimized engine performance with smoother operation and lower fuel consumption, effectively addressing the issue of uneven combustion performance.
Implementation Method 1
an EGR supply conduit extending between an exhaust port of the dedicated EGR cylinder configured to operate on a two-stroke combustion cycle and an intake port of the cylinder configured to operate on a four-stroke combustion cycle, for delivery of exhaust gas exiting the dedicated EGR cylinder configured to operate on a two-stroke combustion cycle to the cylinder configured to operate on a four-stroke combustion cycle for combustion therein
Data Source
AI summary
An internal combustion engine comprises a cylinder configured to operate on a four-stroke combustion cycle, a dedicated EGR cylinder configured to operate on a two-stroke combustion cycle and an EGR supply conduit extending between an exhaust port of the dedicated EGR cylinder and the cylinder configured to operate on a four-stroke combustion cycle for delivery of exhaust gas exiting the dedicated EGR cylinder to the cylinder configured to operate on a four-stroke combustion cycle for combustion therein.