Exhaust Gas Control System Differential Pressure Feedback
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Solution Overview
Problem
The existing exhaust gas control systems for internal combustion engines face inefficiencies in the filter regeneration process due to variations in the oxidation rate of soot based on its crystal structure, leading to inappropriate execution times and incomplete or excessive particulate matter removal, which can result in increased pressure loss, fuel consumption, and engine output deterioration.
Innovation Solution
An exhaust gas control system that includes a pre-regeneration process at a lower temperature and adjusts the execution time of the filter regeneration process based on the speed of change in upstream-downstream differential pressure, taking into account the proportion of defective soot with high lattice defects, to optimize the oxidation and removal of particulate matter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the filter regeneration process is executed without consideration of the difference in oxidation rate due to the crystal structure of soot, then the process can be simplified, but the execution time becomes inappropriate leading to inefficient particulate matter removal
Solution Approach 1:
The patent applies preliminary action by executing a pre-regeneration process before the main filter regeneration process. This pre-regeneration process oxidizes soluble organic fraction accumulated in the filter at a lower temperature, preparing the filter for the subsequent soot oxidation process. By removing soluble organic fraction first, the system prevents interference with soot oxidation and enables more accurate control of the regeneration timing based on differential pressure changes, thereby improving particulate matter removal efficiency without significantly increasing overall process complexity.
2Productivity
If the execution time of the filter regeneration process is extended to ensure complete soot removal, then particulate matter removal efficiency improves, but fuel consumption increases and engine performance deteriorates
Solution Approach 1:
The patent applies feedback control by monitoring the upstream-downstream differential pressure during the pre-regeneration process and using this information to determine the execution time of the subsequent filter regeneration process. The control unit calculates the execution time based on the change in differential pressure during pre-regeneration, which reflects the amount and type of particulate matter present. This feedback mechanism enables precise control of regeneration duration, ensuring complete soot removal while minimizing unnecessary extended operation that would increase fuel consumption and reduce engine performance.
3Stress or pressure
If the filter regeneration process is executed too early, then the filter remains clean and pressure loss is reduced, but the process may be unnecessary and fuel is wasted
Solution Approach 1:
The system uses feedback control by continuously monitoring the upstream-downstream differential pressure across the filter and comparing it against threshold values. The pre-regeneration process is triggered only when the differential pressure exceeds a predetermined threshold, indicating that sufficient particulate matter has accumulated to warrant regeneration. This feedback-based triggering mechanism prevents premature regeneration operations, ensuring that the process is executed only when necessary, thereby avoiding unnecessary fuel consumption while maintaining low back pressure on the engine.
4Loss of energy
If the filter regeneration process is executed too late, then fuel consumption is reduced, but the pressure loss in the filter becomes excessive and engine performance deteriorates
Solution Approach 1:
The system employs feedback control with predetermined threshold values for upstream-downstream differential pressure to determine the optimal timing for pre-regeneration and subsequent filter regeneration processes. When the differential pressure exceeds the threshold, the system triggers pre-regeneration, and based on the differential pressure change during this process, calculates the appropriate timing for full regeneration. This feedback-based timing control ensures regeneration is executed at the optimal moment - not too early (avoiding unnecessary fuel consumption) and not too late (preventing excessive back pressure and engine performance deterioration).
Solution Approach 2:
The patent applies preliminary action by executing a pre-regeneration process before the main filter regeneration process. This pre-regeneration process oxidizes soluble organic fraction accumulated in the filter at a lower temperature, preparing the filter for the subsequent soot oxidation process. By removing soluble organic fraction first, the system prevents interference with soot oxidation and enables more accurate control of the regeneration timing based on differential pressure changes, thereby improving particulate matter removal efficiency without significantly increasing overall process complexity.
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 ensures a suitable execution time for the filter regeneration process, preventing both excessively long or short processes, thereby efficiently oxidizing and removing particulate matter, reducing pressure loss, and maintaining engine performance.
Implementation Method 1
a filter regeneration process for oxidizing and removing particulate matter accumulated in a filter provided in an exhaust passage of the internal combustion engine
Implementation Method 2
a differential pressure sensor configured to detect an upstream-downstream differential pressure in the exhaust passage
Data Source
AI summary
An exhaust gas control system for an internal combustion engine, before execution of a filter regeneration process, executes a pre-regeneration process that is a process of raising a temperature of a filter to a second target temperature lower than a first target temperature and increasing the concentration of NO2 contained in exhaust gas flowing into the filter for a predetermined period. An execution time of the filter regeneration process when a physical quantity that correlates with a speed of change in a detected value of a differential pressure sensor during execution of the pre-regeneration process is large is shorter than an execution time of the filter regeneration process when the physical quantity is small.