Variable-Speed Supercharger for Diluted Engine Boost
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Solution Overview
Problem
Highly diluted internal combustion engines face challenges in achieving thermal efficiency and controlling NOx emissions due to the limitations of three-way catalysts and the complexity of using multiple turbochargers or a turbocharger with a supercharger, which increases cost and packaging complexity.
Innovation Solution
An engine control system utilizing a single supercharger with a variable-speed drive, combined with a passive selective catalytic reduction catalyst system and exhaust gas recirculation, allows for efficient operation by controlling the supercharger speed and recirculating exhaust gases to achieve optimal combustion and emissions control through lean and rich equivalence ratio cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high levels of charge dilution by excess air and recirculated exhaust gas are used to improve thermal efficiency, then thermal efficiency is improved, but NOx emissions control becomes difficult
Solution Approach 1:
The exhaust aftertreatment system is segmented into distinct functional zones: a TWC upstream of the SCR catalyst for ammonia generation, and a passive SCR catalyst downstream for NOx reduction. This segmentation allows the system to handle ammonia storage and NOx reduction separately, enabling effective NOx control under highly diluted conditions.
Solution Approach 2:
The system performs preliminary ammonia generation and storage in the SCR catalyst during rich operation modes before transitioning to lean operation. This preliminary action ensures that ammonia is available in the SCR catalyst before high dilution lean combustion begins, enabling immediate NOx reduction capability when needed.
2Stress or pressure
If multiple turbochargers or a turbocharger in combination with a supercharger are used to achieve high levels of boost, then boost pressure is improved, but cost and packaging complexity increase
Solution Approach 1:
The patent merges the functions of a turbocharger and a supercharger into a single integrated boosting system. The turbocharger provides primary boost while the supercharger supplements at certain operating ranges, achieving high boost pressure levels without the packaging complexity and cost of completely separate systems.
Solution Approach 2:
The single supercharger is designed to perform multiple functions: providing boost pressure across a broad engine operating range, working in conjunction with the turbocharger, and supporting the passive SCR system by enabling the rich/lean cycling required for ammonia generation and storage.
3Object-generated harmful factors
If a passive SCR catalyst system is used to control NOx emissions, then NOx control is improved, but system complexity increases due to the need for ammonia generation and storage
Solution Approach 1:
The passive SCR catalyst system is self-sufficient, generating its own ammonia reactant through the TWC during rich operation modes and storing it within the SCR catalyst structure. This eliminates the need for external ammonia storage tanks, urea injection systems, or complex ammonia delivery infrastructure.
Solution Approach 2:
The system recovers and stores ammonia within the SCR catalyst itself during rich operation, then utilizes this stored ammonia during lean operation for NOx reduction. The TWC upstream serves as both a catalyst and an ammonia generation source, recovering the ammonia needed by the downstream SCR system.
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 system enables flexible engine operation, achieving thermal efficiency and meeting emissions control goals by effectively managing NOx levels and reducing packaging and cost complexities, while maintaining optimal combustion processes across a broad engine operating range.
Implementation Method 1
A supercharger is connected to an air intake passage and the intake manifold
Implementation Method 2
The supercharger includes a variable speed drive. A controller controls the variable speed drive of the supercharger based upon engine speed
Implementation Method 3
a passive selective catalytic reduction catalyst system is in communication with the exhaust passage
Implementation Method 4
An exhaust gas recirculation passage is in communication with the exhaust passage and the air intake passage
Data Source
AI summary
An engine control system includes an internal combustion engine including a plurality of cylinders. An intake manifold is connected to the internal combustion engine. An exhaust manifold is connected to the internal combustion engine. A supercharger is connected to an air intake passage and the intake manifold and includes a variable speed drive. A throttle valve is disposed in the air intake passage. An exhaust passage is in connection with the exhaust manifold. A passive selective catalytic reduction catalyst system is in communication with the exhaust passage. An exhaust gas recirculation passage is in communication with the exhaust passage and the air intake passage and includes an exhaust gas recirculation valve. A controller controls the variable speed drive of the supercharger and the throttle valve and the exhaust gas recirculation valve based upon engine conditions.