Electric Air Compressor Exhaust Moisture Purge
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Solution Overview
Problem
Existing methods for removing moisture from engine exhaust systems, such as increasing airflow through a charge air cooler, are inadequate for addressing condensate accumulation in exhaust systems, leading to prolonged engine open-loop operation, inaccurate sensor measurements, and emissions quality issues due to insufficient vaporization of moisture during engine start/stop conditions.
Innovation Solution
Activating an electric air compressor during a vehicle key-off event to flow compressed air through the engine exhaust system, utilizing existing engine components to purge accumulated moisture, and estimating moisture levels based on ambient humidity, windshield images, and engine operation data to determine the need for moisture removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine operates with short run-time during drive cycle, then fuel economy is improved, but moisture accumulates in the exhaust system causing sensor measurement errors and prolonged open-loop operation
Solution Approach 1:
The system performs preliminary moisture removal action during the key-off event by activating the electric air compressor to flow compressed air through the exhaust system. This anticipatory action prevents moisture accumulation before the next engine start, ensuring sensor readiness and eliminating the need for prolonged open-loop operation when the engine starts again.
2Reliability
If additional components are added to remove condensate from the exhaust system, then moisture removal effectiveness is improved, but device complexity increases
Solution Approach 1:
The electric air compressor, originally designed for a single function in the intake system, is made multi-functional by also enabling it to remove moisture from the exhaust system. The compressor can switch between supplying intake air and routing compressed air through the exhaust system via the EGR valve, eliminating the need for a separate exhaust moisture removal component.
Solution Approach 2:
The system uses its own existing compressed air capability to service the moisture removal need in the exhaust system. Rather than requiring an external or dedicated moisture removal device, the engine's existing compressor serves both intake and exhaust system moisture management needs through intelligent routing.
3Reliability
If the engine run-time during drive cycle is increased to vaporize moisture, then moisture removal is improved, but fuel consumption increases
Solution Approach 1:
Instead of relying on extended engine operation to vaporize moisture, the system performs moisture removal preliminarily during the key-off event using compressed air. This eliminates the need to extend engine run-time for moisture vaporization, maintaining fuel efficiency while ensuring moisture is removed before the next combustion cycle.
4Measurement precision
If the electric air compressor is activated during key-off event to remove moisture, then sensor functionality is improved, but energy consumption during key-off increases
Solution Approach 1:
The system uses a brief, targeted activation of the electric air compressor during the key-off event rather than continuous operation. This short-lived energy input is sufficient to clear moisture from the exhaust system, ensuring sensor readiness for the next engine start while minimizing energy consumption during the off-period.
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
Effectively removes moisture from the exhaust system, expediting oxygen sensor heating, initiating closed-loop engine control, improving fuel economy, and protecting engine components from degradation by eliminating the need for additional condensate removal components.
Implementation Method 1
activating an electric air compressor in the intake system to expel moisture from at least the exhaust system
Implementation Method 2
flow compressed air through the engine exhaust system to remove any accumulated moisture
Implementation Method 3
exhaust temperature may not be high enough to vaporize the moisture accumulated in the exhaust system... flow compressed air through the engine exhaust system to remove any accumulated moisture
Data Source
AI summary
Methods and systems are provided for removing moisture from an engine exhaust system. In one example, a method includes, during a vehicle key-off condition, in response to a higher than threshold exhaust moisture level and a lower than threshold engine run time during an immediately prior drive cycle, operating an electric air compressor to remove the moisture accumulated in the exhaust manifold.