Diesel Engine Lambda Control via Exhaust Combustor
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Solution Overview
Problem
Diesel cycle engines face inefficiencies and pollutant emission challenges due to the use of after-treatment systems (ATS), particularly with urea-based SCR systems, which cause urea crystallization and clogging, and 3-way catalysts are ineffective with lambda factors exceeding 1.
Innovation Solution
The system maintains a lambda value of 1.0 by increasing supercharging pressure to match exhaust backpressure, using a 3-way catalyst downstream of the engine, with coordinated fuel injection and lambda sensor feedback control, replacing traditional ATS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a Diesel cycle engine is equipped with a traditional after-treatment system (ATS) including SCR and DPF, then pollutant emissions (NOx, particulate) are reduced, but the system complexity increases and maintenance issues arise due to urea crystallization and clogging
Solution Approach 1:
The invention extracts and removes the complex SCR and DPF components from the traditional ATS, replacing them with a simplified 3-way catalyst system that achieves similar pollutant reduction without the maintenance issues of urea injection and particulate filtration
Solution Approach 2:
The invention changes the operating parameters of the exhaust system by introducing a combustor that modifies exhaust gas composition and temperature, enabling the 3-way catalyst to operate effectively in a Diesel engine environment where traditionally it would be ineffective due to excess oxygen
2Device complexity
If a 3-way catalyst is used in a Diesel engine, then the system is simplified and maintenance costs are reduced, but the catalyst is traditionally ineffective because Diesel engines operate with lambda factor exceeding 1 (excess oxygen)
Solution Approach 1:
The invention introduces a combustor that burns additional fuel in the exhaust stream, reducing the oxygen concentration and adjusting the lambda factor to approximately 1.0, which creates the appropriate chemical environment for the 3-way catalyst to function effectively in a Diesel engine
Solution Approach 2:
The combustor acts as an intermediary device between the Diesel engine exhaust and the 3-way catalyst, modifying the exhaust gas composition to enable the catalyst to operate effectively by reducing excess oxygen through additional combustion
3Productivity
If supercharging pressure is increased to match exhaust backpressure from turbine and combustor, then engine efficiency is maintained, but the system requires coordinated control of multiple components
Solution Approach 1:
The invention implements a feedback control system using a lambda sensor to monitor exhaust composition and adjust the fuel injection rate to the combustor, ensuring the lambda factor is maintained at approximately 1.0 for optimal 3-way catalyst operation while balancing supercharging pressure with exhaust backpressure
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 maintains engine efficiency while reducing maintenance costs and improving reliability by using a 3-way catalyst, suitable for Diesel engines, and effectively treating pollutants.
Implementation Method 1
a lambda sensor (UEGO) is installed upstream of the second injection means and/or immediately upstream of the ATS, so as to perform a feedback control of the fuel dosage
Implementation Method 2
combustion device... permitting the implementation of a 3-way catalyst, which requires a lambda factor equal to 1.0, without jeopardizing the efficiency of the Diesel cycle engine
Implementation Method 3
a turbine is inserted downstream of said combustion chamber. This turbine causes an increase in the pressure of the exhaust gases upstream of said turbine
Implementation Method 4
the means for injecting fuel into the combustor and the fresh air compressor arranged in the intake line are designed to operate in a coordinated manner
Data Source
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AI summary
Engine system for vehicles and fixed installations based on Diesel cycle comprising, downstream of the Diesel engine (E), second means (N) for introducing and burning fuel and a turbine (T1), which is arranged immediately downstream of the second means (N), and wherein said second means (N) are controlled so as to maintain the lambda value in the exhaust gases entering a pollutant reduction device (ATS) equal to 1.0.