Intake Oxygen Control for Lean NOx Trapping Engines
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Solution Overview
Problem
Existing engine technologies face challenges in reducing NOx emissions while improving thermal efficiency, as oxygen-enriched combustion increases NOx emissions and fuel consumption, and lean NOx trapping requires additional fuel for effective NOx reduction.
Innovation Solution
An intake oxygen concentration control system that includes an exhaust turbocharging system, an intake system, a lean NOx trapping post-treatment system, and a control system, which controls oxygen concentration in engine cylinders to optimize combustion conditions, using oxygen-rich and oxygen-deficient gases to enhance fuel efficiency and reduce NOx emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If oxygen-enriched combustion is used to improve thermal efficiency, then fuel economy is improved, but NOx emissions increase
Solution Approach 1:
The patent applies local quality by providing different oxygen concentrations to different cylinders. Specifically, three cylinders receive oxygen-enriched air (30-40% oxygen) to achieve complete combustion and high thermal efficiency, while one cylinder receives normal air (21% oxygen) to act as a NOx reduction zone. This spatial differentiation allows each cylinder to have optimized combustion characteristics, resolving the contradiction between fuel economy and NOx emissions at the system level.
2Object-generated harmful factors
If lean NOx trapping technology is used to reduce NOx emissions, then NOx removal rate increases, but fuel consumption increases
Solution Approach 1:
The patent segments the combustion system into multiple functional zones by dividing the four cylinders into different combustion modes. Three cylinders operate in lean combustion mode (oxidizing atmosphere) for NOx storage, while one cylinder operates in rich combustion mode (reducing atmosphere) for NOx reduction. This segmentation eliminates the need for extensive fuel injection required by conventional lean NOx trapping systems, as the rich combustion zone is naturally created by oxygen-deficient intake air rather than excess fuel injection.
3Temperature
If oxygen-enriched combustion is used to improve thermal efficiency, then flame temperature increases, but cylinder temperature rises causing more NOx
Solution Approach 1:
The patent converts the harmful effect of high temperature (which causes NOx formation) into a beneficial system feature by creating a multi-zone temperature distribution. Three cylinders operate at high flame temperatures for efficient combustion, while one cylinder operates at lower temperatures to serve as a NOx reduction zone. The exhaust from the high-temperature cylinders provides the heat necessary for the lean NOx trapping process in the low-temperature cylinder, transforming the harmful high-temperature NOx formation into a useful thermal resource for 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
The system achieves complete fuel combustion, improved thermal efficiency, and reduced NOx emissions by ensuring all cylinders receive optimal oxygen levels during lean combustion and minimizes fuel consumption during rich combustion cycles, thereby enhancing engine performance and reducing emissions.
Implementation Method 1
an outlet of the oxygen-enriched membrane communicates with an oxygen-rich gas mixing chamber via an oxygen-rich gas branch, and an outlet of the oxygen-enriched membrane communicates with an oxygen-deficient gas mixing chamber via an oxygen-deficient gas branch
Implementation Method 2
The exhaust turbocharging system includes a turbine, and a revolving shaft of the turbine is fixedly connected with a revolving shaft of a compressor coaxially
Implementation Method 3
an intake pipe at an exhaust side of the air filter communicates with a gas inlet of the compressor, and a gas outlet of the compressor communicates with inlets of three branches
Implementation Method 4
The control system includes an electronic control unit (ECU) that is connected to the engine, the first air flow control valve, the second air flow control valve, the oxygen-deficient gas flow control valve, the mixed gas flow control valve, and the oxygen sensor via control lines, separately
Implementation Method 5
the lean NOx trapping technology is an effective post-treatment technology to reduce NOx emissions. Oxidizing and reducing atmospheres are created for a lean NOx trapping device through periodic lean combustion and rich combustion in an engine
Data Source
AI summary
The present disclosure discloses an intake oxygen concentration control system suitable for an engine with lean NOx trapping technology. The system adopts an exhaust turbocharging device to provide a pressure difference for an oxygen-enriched membrane to generate oxygen-rich and oxygen-deficient gases, and controls the intake oxygen concentration of different cylinders by adjusting the opening of flow control valves to match lean and rich combustion cycles of a lean NOx trapping system. In a lean combustion cycle, all four cylinders are filled with an oxygen-rich gas, which can make the combustion more complete and improve the thermal efficiency and fuel economy. In a rich combustion cycle, one of the four cylinders is filled with an oxygen-deficient gas, and the other three cylinders are filled with air or an oxygen-rich gas with a low concentration, so that less fuel is required to create a reducing atmosphere to realize the release and reduction of NOx in a lean NOx trapping device, thereby reducing the fuel consumption and ensuring the output power of the other three cylinders.