Engine Rebreathe Mode Transitions for NOx and Shudder Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing engine emissions reduction systems are complex and require additional hardware and software, impacting engine performance and fuel efficiency, while also failing to effectively reduce emissions without introducing noise or shudder.
Innovation Solution
Implementing a rebreathe engine operating mode where exhaust valves are actuated during the intake phase, allowing exhaust gases to recirculate and mix with intake gases, promoting auto-ignition and increasing exhaust gas temperature for improved catalytic conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If additional hardware and software are added to reduce emissions, then emissions reduction is improved, but device complexity increases and engine performance deteriorates
Solution Approach 1:
The exhaust system serves dual purposes: it extracts exhaust gases for emission control and simultaneously uses those same exhaust gases to heat the intake charge. The system is self-sufficient, using its own byproducts (exhaust gases) to improve combustion efficiency and reduce emissions without requiring external energy sources or additional complex subsystems.
Solution Approach 2:
The exhaust manifold and associated hardware perform multiple functions: they collect and route exhaust gases away from the cylinders, uses those exhaust gases to heat the incoming air-fuel mixture, and thereby contribute to emission reduction. This multi-functionality eliminates the need for separate dedicated emission control systems.
2Object-generated harmful factors
If additional hardware and software are added to reduce emissions, then emissions reduction is improved, but fuel efficiency deteriorates
Solution Approach 1:
The system changes the temperature parameter of the intake charge by heating it with exhaust gases. This parameter change improves combustion efficiency and completeness, which enhances fuel utilization and reduces emissions simultaneously, rather than creating a trade-off between the two.
3Object-generated harmful factors
If exhaust valves are actuated during intake phase, then emissions reduction is improved, but engine stability deteriorates due to potential noise and shudder
Solution Approach 1:
The valve actuation system is made dynamic and adaptive. The control system monitors engine operating conditions and adjusts valve actuation timing and duration accordingly. This dynamic control allows the system to achieve emission reductions while maintaining engine stability by avoiding excessive or improperly timed valve actuation that would cause noise or shudder.
Solution Approach 2:
The system incorporates feedback control where the ECU monitors engine performance parameters and adjusts the valve actuation strategy in real-time. This feedback mechanism ensures that emission control actions do not push the engine into unstable operating regions, thereby preventing noise and shudder while still achieving NOx reduction.
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
Reduces NOx emissions and enhances fuel efficiency by warming the intake gas mixture, facilitating efficient catalytic conversion and maintaining optimal exhaust temperatures.
Implementation Method 1
exhaust valves are actuated during the intake phase, allowing exhaust gases to recirculate and mix with intake gases
Implementation Method 2
promoting auto-ignition and increasing exhaust gas temperature for improved catalytic conversion
Implementation Method 3
increasing exhaust gas temperature for improved catalytic conversion
Data Source
AI summary
An engine includes pistons, a crankshaft, cylinders, an intake manifold, an exhaust manifold, intake valves, exhaust valves, a fuel rail, and an Electronic Control Unit (ECU). The ECU coordinates operations of the intake valves, the exhaust valves, and the fuel injectors based upon a position of the crankshaft to control the engine to operate in two modes. The two modes include a typical engine operating mode and a rebreathe engine operating mode. The typical engine operating mode includes the ECU controlling the exhaust valves to be actuated after the intake valves are actuated. The rebreathe engine operating mode includes the ECU controlling the exhaust valves to be actuated both during and after the intake valves are actuated. The ECU also controls a Start of Injection (SOI) of the fuel injectors to be retarded during the typical engine operating mode and to be advanced during the rebreathe engine operating mode.