Particulate Filter Regeneration Using Compressed Air
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Solution Overview
Problem
Existing methods for particulate filter regeneration during engine non-combusting conditions, such as engine start-stop and deceleration fuel shut-off, are inefficient due to the time required for vacuum buildup and potential temperature drops, leading to incomplete regeneration and increased exhaust back pressure.
Innovation Solution
Activating an electric booster to route compressed air to the particulate filter during non-combusting conditions, utilizing existing engine components like a turbocharger and electric compressor, to facilitate regeneration by maintaining a high oxygen content and utilizing residual exhaust heat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a vacuum pump is used to draw ambient air through the PF during engine-off conditions, then oxygen is supplied for PF regeneration, but the time required for vacuum buildup causes the PF temperature to drop below the threshold needed for regeneration
Solution Approach 1:
The system performs preliminary action by storing compressed air in a tank before engine-off conditions occur. When regeneration is needed, the pre-stored compressed air is immediately deployed, eliminating the time delay associated with vacuum pump operation and ensuring the PF temperature remains above the regeneration threshold.
Solution Approach 2:
The invention replaces the mechanical vacuum pump system with a compressed air storage and delivery system. This substitution eliminates the need for vacuum buildup time, as compressed air can be delivered immediately through electronic control valves, directly addressing the time loss issue while still providing the necessary oxygen for regeneration.
2Quantity of substance
If a high powered vacuum pump is used to remove air from the exhaust system for vacuum generation, then sufficient oxygen can reach the PF, but the PF temperature drops below the threshold temperature before oxygen arrives
Solution Approach 1:
Compressed air is pre-stored in a tank during engine operation when temperatures are high. During engine-off regeneration, this pre-stored air is immediately delivered to the PF, ensuring both oxygen availability and maintenance of regeneration temperature without the delay that would cause temperature drop.
Solution Approach 2:
The high powered vacuum pump is replaced with an electronically controlled compressed air delivery system. This substitution allows for instantaneous oxygen delivery through solenoid valves, eliminating the time lag that causes temperature drop, while the compressed air itself can be heated to maintain regeneration temperature.
3Temperature
If the engine is kept running to maintain PF temperature for regeneration, then sufficient temperature is maintained for soot oxidation, but the engine continues to consume fuel and emit emissions
Solution Approach 1:
The system uses residual heat from the exhaust system and engine components to maintain PF temperature during shutdown. Compressed air is heated as it passes through hot exhaust manifolds and catalysts, providing self-heating without additional fuel consumption, enabling regeneration during engine-off conditions.
Solution Approach 2:
The system recovers waste heat from the exhaust system, engine blocks, and catalysts that would otherwise be lost during shutdown. This recovered thermal energy is used to heat the compressed air for PF regeneration, eliminating the need to keep the engine running and avoiding unnecessary fuel consumption and emissions.
4Temperature
If regeneration is delayed until engine combustion is active, then sufficient temperature and oxygen are available, but the PM load on the PF increases and exhaust back pressure adversely affects engine performance
Solution Approach 1:
Compressed air is pre-stored and ready for immediate deployment when engine shutdown occurs with high PM load. The system proactively initiates regeneration during shutdown rather than waiting for the next combustion cycle, reducing PM accumulation and preventing exhaust back pressure from degrading engine performance.
Solution Approach 2:
The exhaust system's residual heat and thermal mass are utilized to maintain regeneration temperature without active engine combustion. The catalyst and exhaust manifolds continue to retain heat long enough to enable regeneration during brief shutdown periods, allowing the system to self-maintain regeneration conditions without fuel consumption.
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 allows for efficient particulate filter regeneration during engine-off conditions, maintaining a clean filter, improving emissions quality and engine performance without the need for additional components, especially in hybrid vehicles with short engine run-times.
Implementation Method 1
activating an electric booster in an intake system of the engine to route compressed air to the PF for PF regeneration
Implementation Method 2
Flow of compressed air may provide the motive force to flow heated air from an exhaust catalyst coupled to the exhaust passage upstream of the PF to the PF to further expedite the regeneration
Implementation Method 3
at the elevated temperature, in the presence of oxygen from the compressed air, the PM may be burnt and the PF may be regenerated
Data Source
AI summary
Methods and systems are provided for regenerating an exhaust particulate filter during an engine non-combusting condition. In one example, a method may include, responsive to a higher than first threshold soot load on the PF and a higher than threshold PF temperature, regenerating the PF by flowing compressed air through the PF via operation of an electric booster coupled to the intake manifold.