Engine Intake Moisture Control via Cylinder Valve Sealing
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Solution Overview
Problem
Existing methods for reducing water accumulation in engine intakes, such as increasing airflow through a charge air cooler, are ineffective during engine non-combusting conditions like hybrid vehicle propulsion or engine idle-stop scenarios, leading to moisture condensation and subsequent engine misfires due to ambient humidity.
Innovation Solution
The method involves selectively closing deactivatable cylinder valves during high ambient humidity conditions when the engine is not combusting and using recirculated hot exhaust gas to evaporate moisture in the intake manifold, then reactivating these cylinders first upon engine restart to prevent condensate ingestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine is operated in non-combusting conditions (hybrid propulsion, idle-stop) during high ambient humidity, then fuel economy is improved, but moisture condensation occurs in the intake manifold causing engine misfires
Solution Approach 1:
The system performs preliminary heating of the intake manifold using hot exhaust gas recirculation before the engine is restarted after non-combusting operation. This preemptive action raises the intake manifold temperature above the dew point, preventing moisture condensation from forming in the first place, thereby eliminating misfire risks while maintaining fuel economy benefits during idle-stop or hybrid propulsion modes.
2Reliability
If deactivatable cylinder valves are held closed during non-combusting conditions, then moisture ingestion into cylinders is reduced, but device complexity increases
Solution Approach 1:
The existing deactivatable cylinder valve mechanism, originally designed for fuel economy optimization, is repurposed to serve a dual function: it now also prevents moisture ingestion during non-combusting conditions. By holding these same valves closed during idle-stop or hybrid propulsion, the system protects cylinders from condensate without adding new hardware, leveraging the existing multi-functional capability of the valve system to simultaneously address both fuel economy and combustion stability concerns.
3Reliability
If hot exhaust gas is recirculated to the intake manifold during non-combusting conditions, then intake manifold temperature increases preventing condensation, but energy loss increases
Solution Approach 1:
The system recovers waste heat from the exhaust gas that would otherwise be discarded to the atmosphere. By routing this hot exhaust gas through the EGR system into the intake manifold, the thermal energy is reused to maintain intake manifold temperature above the dew point, preventing condensation. This transforms a wasted energy resource into a useful heating source, eliminating misfire risks without requiring additional fuel input or external heating systems.
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 reduces water accumulation and misfire occurrences by ensuring the intake manifold temperature increases before resuming combustion in non-deactivatable cylinders, enhancing combustion stability and reducing the likelihood of misfires.
Implementation Method 1
recirculated hot exhaust gas to evaporate moisture in the intake manifold
Implementation Method 2
evaporate moisture in the intake manifold
Implementation Method 3
humid air may condense in the intake manifold
Data Source
AI summary
Methods and systems are provided for reducing accumulation of condensate in an engine intake during an engine non-combusting condition. In one example, during an engine non-combusting condition, responsive to a higher than threshold ambient humidity and a lower than threshold intake manifold temperature, intake and exhaust valves of deactivatable cylinders may be closed in order to seal the cylinders and during an immediately subsequent engine combusting condition, the intake and exhaust valves of the deactivatable cylinders may be activated and combustion may be resumed in the deactivatable cylinders before starting combustion in non-deactivatable cylinders. Also, during the engine non-combusting condition, residual hot exhaust may be recirculated to the intake manifold to evaporate condensate in the intake manifold.