Particulate Filter Temperature Control via Boosted Exhaust Recirculation
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Solution Overview
Problem
During the regeneration of a particulate filter in an internal combustion engine, the temperature of the filter can uncontrollably increase when engine speed drops to idle, leading to excessive thermal stress due to reduced cooling effects and increased heat generation from particulate matter combustion.
Innovation Solution
The method involves measuring engine speed and controlling the particulate filter temperature by boosting the engine with recirculated exhaust gases, which increases the mass flow rate and reduces oxygen concentration, thereby maintaining a proper cooling effect and preventing excessive thermal stress. This is achieved through close-loop control adjustments of air mass flow rate and oxygen concentration, using an electric compressor for independent boosting and an exhaust gas recirculation valve for efficient recirculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the internal combustion engine operates at low engine speed during regeneration, then the regeneration process can be maintained, but the cooling effect of exhaust gases is significantly reduced causing uncontrollable temperature increase
Solution Approach 1:
The control unit activates the electric compressor before the engine speed drops to critical levels, ensuring that sufficient exhaust gas mass flow rate is maintained throughout the regeneration process. This preliminary action prevents the temperature from rising uncontrollably by ensuring cooling capacity is already in place.
Solution Approach 2:
The electric compressor acts as an intermediary device that decouples the relationship between engine speed and exhaust gas mass flow rate. By mechanically forcing exhaust gas circulation independent of engine speed, it mediates between the low-speed operating condition and the required cooling effect.
2Adaptability or versatility
If the engine speed drops to idle speed during regeneration, then low-speed operation is possible, but the temperature may increase uncontrollably due to reduced mass flow rate
Solution Approach 1:
The electric compressor replaces the natural mechanical coupling between engine crankshaft rotation and exhaust gas flow. Instead of relying on engine speed to drive exhaust circulation, an independently controlled electric motor drives the compressor to maintain flow, substituting mechanical engine-driven flow with electrically-controlled flow.
Solution Approach 2:
The system changes the operating parameter of exhaust gas mass flow rate independently from engine speed by activating the electric compressor. This allows the mass flow rate parameter to be decoupled from engine speed, enabling stable temperature control across varying engine speeds including idle conditions.
3Object-affected harmful factors
If recirculated exhaust gases are supplied during regeneration, then oxygen concentration is reduced preventing excessive heat generation, but additional system complexity is required
Solution Approach 1:
The electric compressor serves multiple functions: it maintains exhaust gas mass flow rate for cooling purposes and simultaneously enables exhaust gas recirculation to control oxygen concentration. This multi-functionality reduces the need for separate dedicated systems for each function.
Solution Approach 2:
The control unit continuously monitors temperature and oxygen concentration parameters and adjusts the electric compressor operation and recirculation valve positioning accordingly. This feedback control ensures that the harmful heat generation is prevented while maintaining efficient regeneration.
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 solution allows for effective regeneration of the particulate filter at low engine speeds without causing excessive thermal stress, ensuring the filter's efficiency is restored while minimizing thermal damage.
Implementation Method 1
supplying the internal combustion engine with an amount of recirculated exhaust gases. The recirculated exhaust gases have the effect of reducing the quantity of oxygen that flows through the particulate filter
Implementation Method 2
boosting the internal combustion engine has the effect of increasing the mass flow rate of exhaust gases that flow through the particulate filter, thereby guaranteeing a proper cooling effect on the particulate filter
Implementation Method 3
the temperature of the particulate filter is affected by other factors, including the heat generated by the combustion of the particulate matter
Data Source
AI summary
A method and apparatus for cleaning up a particulate filter of an internal combustion engine is provided. The internal combustion engine is operated to regenerate the particulate filter measuring. During the regeneration, a value of an engine speed is determined. A temperature of the particulate filter is controlled, if the measured value of the engine speed is smaller than or equal to a predetermined threshold value thereof. The particulate filter temperature is controlled by boosting the internal combustion engine and supplying the internal combustion engine with an amount of recirculated exhaust gases.