Exhaust Particulate Filter Regeneration via Diverter Valve and Heater
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Solution Overview
Problem
Existing engine exhaust systems face challenges in reducing particulate emissions while maintaining fuel economy and preventing premature degradation of particulate filters, as excessive oxygen flow during engine shutdown can lead to filter overheating and reduced drivability.
Innovation Solution
A method and system that direct engine exhaust gas to an exhaust particulate filter during cold start conditions and bypass it during warm engine combustion, using an exhaust diverter valve and heater to control filter temperature for efficient regeneration without excessive heat stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If oxygen flow to the filter is increased during DFSO or engine shutdown events to regenerate the particulate filter, then particulate removal is improved, but filter temperature increases excessively leading to premature filter degradation
Solution Approach 1:
The system performs preliminary heating of the particulate filter using an electric heater before directing high-oxygen exhaust gas to the filter during DFSO events. This pre-heating ensures the filter reaches the necessary temperature for effective particulate oxidation without requiring excessive oxygen flow that would cause overheating and degradation.
Solution Approach 2:
The system uses periodic regeneration cycles where the exhaust diverter valve directs high-oxygen exhaust gas to the particulate filter for a limited duration during DFSO events. This periodic action allows sufficient time for particulate oxidation while preventing excessive temperature accumulation that would lead to filter degradation.
2Reliability
If DFSO duration is limited to mitigate excessive filter temperature increases, then filter degradation is reduced, but fuel economy and drivability are reduced
Solution Approach 1:
The electric heater pre-heats the particulate filter before DFSO events, reducing the duration needed for regeneration. This allows DFSO to be maintained for sufficient fuel economy and drivability while achieving effective particulate removal in a shorter, controlled time period.
Solution Approach 2:
The electric heater acts as an intermediary that provides the necessary thermal energy for regeneration independently of exhaust gas temperature and duration. This decouples the regeneration effectiveness from DFSO duration, allowing DFSO to be optimized for fuel economy and drivability without compromising filter regeneration.
3Object-generated harmful factors
If the particulate filter is used during cold start conditions, then emissions are reduced, but the filter size must be larger to handle the additional thermal stress
Solution Approach 1:
The electric heater pre-heats the particulate filter during cold start conditions before high-oxygen exhaust gas is directed to it. This preliminary heating protects the filter from thermal shock and stress, allowing the use of a smaller filter design that would otherwise be vulnerable to damage during cold operation.
Solution Approach 2:
The system changes the thermal parameters of the filter by actively heating it to operational temperature before exposing it to high-oxygen exhaust during cold starts. This parameter change (temperature) enables the filter to withstand thermal conditions that would otherwise require a larger, more robust design.
4Productivity
If the particulate filter temperature is not raised during warm engine conditions, then fuel economy is improved, but regeneration cannot occur
Solution Approach 1:
The system employs periodic regeneration events during warm engine operation when the engine is decelerating or under light load. During these periodic intervals, the exhaust diverter valve redirects high-oxygen exhaust to the filter for regeneration, while maintaining normal operation during other periods to preserve fuel economy.
Solution Approach 2:
The exhaust diverter valve acts as an intermediary that selectively routes high-oxygen exhaust gas to the particulate filter during specific warm engine conditions. This allows regeneration to occur during otherwise fuel-efficient operation without continuously compromising fuel economy.
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 reliable filter regeneration during shutdown events, maintains fuel economy and drivability, reduces filter size and manufacturing costs, and improves reliability by optimizing particulate filter operation.
Implementation Method 1
an exhaust particulate filter heater... heating the exhaust particulate filter when an exhaust particulate filter temperature decreases below a threshold filter temperature
Implementation Method 2
regenerating the exhaust particulate filter... oxidize the PM... raising the filter temperature to oxidize the PM
Data Source
AI summary
Methods and systems are provided for filtering particulate matter in an exhaust passage of an engine system. In one example, a method may include during a cold start condition comprising an engine temperature being less than a threshold engine temperature, directing engine exhaust gas to an exhaust particulate filter, and during a warm engine condition, directing engine exhaust gas to bypass the exhaust particulate filter, wherein the warm engine condition comprises the engine temperature being greater than or equal to the threshold engine temperature and fuel being combusted in the engine. In this way, the exhaust particulate filter may be reliably regenerated during engine shutdown events such as DFSOs while reducing filter degradation, and lowering PM emissions.