Crankcase Ventilation Valve Layout to Prevent Emulsion and Freezing
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Solution Overview
Problem
Existing engine ventilation systems face issues with emulsion formation and freezing due to moisture condensation in unidirectional valves exposed to blow-by gas, leading to operational inefficiencies and potential damage.
Innovation Solution
The engine design includes a unidirectional valve directly attached to the crankcase, with a coupling passage guiding discharged air in a direction different from the discharge direction, and a valve housing for quick warming, preventing emulsion and freezing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a unidirectional valve is installed in the air introduction passage to restrict backflow, then gas backflow is prevented, but moisture condensation occurs inside the valve leading to emulsion
Solution Approach 1:
The unidirectional valve is extracted from the air introduction passage and repositioned to be directly attached to the crankcase. This separation removes the valve from the condensation-prone environment while maintaining its backflow prevention function, as the valve now operates in the warmer crankcase interior where moisture condensation is minimized.
Solution Approach 2:
A coupling passage is introduced as an intermediary component to connect the unidirectional valve outlet to the crankcase interior. This coupling passage redirects the discharged air away from the air introduction passage, preventing moisture-laden air from condensing in the valve while still achieving effective crankcase ventilation.
2Productivity
If air is discharged directly into the crankcase, then ventilation is achieved, but air discharge onto the oil surface causes emulsion and increases oil consumption
Solution Approach 1:
The coupling passage changes the spatial dimension of air discharge by extending in a direction different from the valve discharge direction. This redirects the air flow path to enter the crankcase interior away from the oil surface, maintaining ventilation effectiveness while preventing oil agitation and emulsion formation.
Solution Approach 2:
The coupling passage creates a localized discharge zone within the crankcase that is spatially separated from the oil surface. By controlling where the air is discharged within the crankcase interior, the system maintains effective ventilation while avoiding the harmful interaction between discharged air and oil.
3Reliability
If the unidirectional valve is positioned to prevent backflow, then gas flow control is improved, but the valve is exposed to cold temperatures causing moisture condensation
Solution Approach 1:
The unidirectional valve is merged with the crankcase structure by direct attachment, positioning the valve within the warm crankcase interior. This merging places the valve in a thermally favorable environment where the crankcase walls and internal heat maintain a temperature above the dew point, preventing moisture condensation while preserving backflow prevention functionality.
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
Suppresses emulsion and freezing, ensuring efficient ventilation and reducing oil consumption by minimizing air discharge onto the oil surface, thereby maintaining optimal engine operation.
Implementation Method 1
a coupling passage that guides, into the crankcase, air discharged from the unidirectional valve. The coupling passage extends in a direction different from a direction in which air is discharged from the unidirectional valve.
Implementation Method 2
a unidirectional valve attached to the crankcase and configured to restrict a flow of gas from the crankcase toward the intake passage
Implementation Method 3
When the temperature of the unidirectional valve is relatively low, the moisture in the blow-by gas is condensed inside or around the unidirectional valve, and the condensed moisture is mixed with oil. As a result, emulsion may occur.
Data Source
AI summary
An engine performs ventilation of blow-by gas by introducing air from an intake passage into a crankcase. The engine includes an air introduction passage that fluidly connects the intake passage to the crankcase, a unidirectional valve attached to the crankcase and configured to restrict a flow of gas from the crankcase toward the intake passage through the air introduction passage, and a coupling passage that guides, into the crankcase, air discharged from the unidirectional valve. The coupling passage extends in the direction that is different from a direction in which air is discharged from the unidirectional valve.