EGR Valve Compensation for Aftertreatment Flow Restriction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The aftertreatment apparatus in internal combustion engines becomes increasingly clogged with deposits, leading to a self-reinforcing feedback loop of soot generation and flow restriction, which diverts more exhaust into the exhaust gas recirculation circuit, reducing oxygen availability and necessitating premature replacement.
Innovation Solution
A controller determines a desired proportion of exhaust gas for the exhaust gas recirculation circuit and adjusts the exhaust gas recirculation valve position using a compensation function to maintain consistent mass flow distribution by accounting for aftertreatment system aging through pressure delta calculations, thereby compensating for flow restrictions due to deposits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the aftertreatment apparatus is used over time, then it becomes filled with deposits of soot and ash, but this increases restriction of exhaust gas flow in the aftertreatment system
Solution Approach 1:
The controller continuously monitors the actual proportion of exhaust gas flowing through the aftertreatment apparatus versus the desired proportion, and adjusts the exhaust gas recirculation valve position accordingly. This closed-loop feedback system compensates for increasing flow restriction due to deposits, maintaining optimal exhaust distribution throughout the service life of the aftertreatment apparatus.
Solution Approach 2:
The system dynamically changes the operating parameter (exhaust gas recirculation valve position) based on the inferred aftertreatment flow restriction value. By adjusting the valve position to compensate for increasing flow restriction, the system maintains the desired exhaust gas distribution ratio despite the aftertreatment apparatus being filled with deposits over time.
2Quantity of substance
If more exhaust is diverted to the exhaust gas recirculation circuit due to aftertreatment flow restriction, then oxygen availability in the combustion chamber decreases, but this leads to increased soot generation
Solution Approach 1:
The controller uses feedback from the actual exhaust gas proportion measurement to adjust the exhaust gas recirculation valve, preventing excessive diversion of exhaust gas to the recirculation circuit. This maintains adequate oxygen availability in the combustion chamber and prevents increased soot generation that would result from oxygen-deficient combustion conditions.
Solution Approach 2:
The system proactively compensates for flow restriction before it causes harmful effects. By continuously adjusting the exhaust gas recirculation valve based on inferred flow restriction values, the system prevents the condition where excessive exhaust diversion would lead to oxygen starvation and increased soot formation.
3Ease of operation
If the exhaust gas recirculation valve position is fixed, then the proportion of exhaust to aftertreatment apparatus is determined by valve position, but this proportion changes as aftertreatment flow restriction increases with use
Solution Approach 1:
The system transitions from a static valve position control to a dynamic control where the exhaust gas recirculation valve position is continuously adjusted based on the inferred aftertreatment flow restriction value. This dynamic adjustment compensates for changing flow conditions, maintaining stable mass flow distribution to the aftertreatment apparatus throughout its service life.
Solution Approach 2:
The controller changes the valve position parameter in response to changes in aftertreatment flow restriction. By dynamically adjusting this parameter based on monitored conditions, the system maintains consistent exhaust gas distribution ratios despite the aftertreatment apparatus accumulating deposits over time.
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
Maintains consistent mass flow distribution between the aftertreatment apparatus and exhaust gas recirculation circuit throughout the engine's life, preventing excessive soot generation and prolonging the aftertreatment apparatus's lifespan.
Implementation Method 1
an exhaust gas recirculation valve for regulating flow of exhaust through the exhaust gas recirculation circuit
Implementation Method 2
to determine, based on the proportion of exhaust gas to be directed to the exhaust gas recirculation circuit, a baseline value for an extent to which to open the exhaust gas recirculation valve
Data Source
AI summary
An engine assembly comprises an exhaust gas recirculation circuit, an aftertreatment apparatus and a controller. The controller is configured to determine a desired proportion of exhaust gas to be directed to the exhaust gas recirculation circuit. The controller is further configured to determine, based on the proportion of exhaust gas to be directed to the exhaust gas recirculation circuit, a baseline value for an extent to which to open the exhaust gas recirculation valve for a clean aftertreatment apparatus. The controller is further configured to determine a compensation function based on an inferred aftertreatment flow restriction value. The controller is further configured to control the extent to which the exhaust gas recirculation valve is open based on the baseline value modified by the compensation function in order to maintain the desired proportion of exhaust gas to be directed to the exhaust gas recirculation circuit.