Split Exhaust Manifold Engine Control for Compressor Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In split exhaust engine systems, high engine speeds and increased exhaust gas recirculation (EGR) can lead to compressor degradation due to elevated temperatures and speeds, potentially causing over-speed, over-temperature, and condensation issues, which existing methods struggle to mitigate effectively.
Innovation Solution
The method involves adjusting gas flow by decreasing gas flow from the first exhaust manifold to the intake passage upstream of the compressor and increasing gas flow to the second exhaust manifold in response to specific engine operating conditions, such as threshold temperatures and speeds, to reduce compressor degradation and prevent residual gas trapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EGR flow is increased to reduce combustion temperatures and knock, then engine efficiency and knock resistance improve, but compressor temperature and speed increase causing degradation
Solution Approach 1:
The exhaust system is segmented into two separate manifolds: a first exhaust manifold that routes exhaust to the intake passage for EGR, and a second exhaust manifold that routes exhaust to the turbine. This segmentation allows independent control of EGR flow and turbine exhaust flow, enabling optimization of both knock resistance and compressor protection without compromising either function.
2Object-affected harmful factors
If EGR valve is closed to reduce EGR flow and protect compressor, then compressor temperature and speed decrease, but residual exhaust gases become trapped in cylinders and first exhaust manifold
Solution Approach 1:
By separating the exhaust system into two manifolds with independent valve control, the system can selectively open the second exhaust manifold valves to vent residual gases while keeping the first exhaust manifold closed for EGR control. This eliminates residual gas trapping without compromising compressor protection.
Solution Approach 2:
The second exhaust manifold acts as an intermediary pathway that provides an alternative route for residual exhaust gases to escape when the first exhaust manifold is closed. This intermediary system allows the EGR valve to be closed for compressor protection while preventing harmful residual gas accumulation through the second manifold pathway.
3Productivity
If high engine speed operation is pursued to increase power output, then productivity improves, but compressor over-speed and condensation issues occur
Solution Approach 1:
The dual exhaust manifold system allows the first manifold to be closed during high-speed operation, preventing excessive EGR flow to the compressor. This segmentation enables the engine to operate at high speeds for increased power output while protecting the compressor from over-speed damage through selective isolation of the EGR pathway.
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 compressor degradation, minimizes pressure buildup in the first exhaust manifold, and enhances engine efficiency by directing exhaust gases and blowthrough air to the turbine, thereby lowering combustion temperatures and improving turbine work efficiency.
Implementation Method 1
flowing a first portion of the exhaust gas (e.g., higher pressure exhaust) through the turbine and a higher pressure exhaust passage
Implementation Method 2
flowing a second portion of the exhaust gas (e.g., lower pressure exhaust) and blowthrough air to the compressor inlet
Data Source
AI summary
Methods and systems are provided for operating a split exhaust engine system that provides blowthrough air and exhaust gas recirculation to an intake passage via a first exhaust manifold and exhaust gas to an exhaust passage via a second exhaust manifold. In one example, a method may include decreasing gas flow from the first exhaust manifold to the intake passage, upstream of a compressor, where a first set of exhaust valves are exclusively coupled to the first exhaust manifold, in response to a condition of the compressor. Further, the method may include increasing gas flow from the first exhaust manifold to an exhaust passage coupled to a second exhaust manifold coupled to a second set of exhaust valves, in response to the decreasing gas flow.