Oil Mist Separator Check Valve Backflow Prevention
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Solution Overview
Problem
Existing oil mist separator check valves are prone to unstable opening and closing operations due to weight and pressure differences, and may allow backflow of oil into the intake system when the pressure difference is low, especially when the check valve's own weight is increased by oil droplet adhesion.
Innovation Solution
A check valve with a spherical valve head portion and a stem portion, where the valve head is movable within a fine clearance in the drain pipe, ensuring reliable operation by utilizing pressure differences and buoyancy forces to maintain the valve in a closed state, and opening when oil accumulates, preventing backflow and excessive oil accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the check valve's own weight is increased due to adhesion of oil droplets, then the valve body can remain closed under normal conditions, but the opening and closing operations become unstable and the valve may fail to close properly when pressure difference is low
Solution Approach 1:
The check valve is divided into two separate functional parts: a valve body that opens and closes the oil discharge hole, and a valve head portion that fits into the drain pipe with fine clearance. This segmentation allows the valve head portion to respond to pressure differences and oil accumulation independently, while the valve body provides stable sealing, thus resolving the contradiction between reliable closing and stable operation.
Solution Approach 2:
The valve head portion acts as an intermediary element between the pressure difference environment and the valve body. It fits into the drain pipe with fine clearance and moves in response to pressure differences and oil accumulation, thereby controlling the opening and closing of the valve body without being directly affected by oil droplet adhesion, ensuring stable operation.
2Productivity
If the clearance between the check valve in open state and the lower end of the drain pipe is large, then oil can flow out when accumulated, but the check valve is not sucked and kept open due to its own weight when pressure difference is small
Solution Approach 1:
The valve head portion is designed with a specific local quality by fitting into the drain pipe with fine clearance at a specific location. This fine clearance creates sufficient resistance to prevent the valve from staying open when pressure difference is small, while still allowing oil to flow out when the valve is intentionally opened, thus resolving the contradiction between discharge efficiency and closing reliability.
3Device complexity
If the check valve is designed to close the oil discharge hole from outside the drain pipe, then the structure is simple, but the valve cannot respond effectively to pressure differences and may allow backflow
Solution Approach 1:
The valve head portion is nested inside the drain pipe with fine clearance, while the valve body remains outside closing the oil discharge hole. This nested configuration allows the valve head portion to respond to pressure differences internally, while the valve body provides external sealing, achieving effective backflow prevention without excessive structural complexity.
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
The check valve effectively suppresses backflow of blow-by gas and oil into the intake system, ensuring stable operation and preventing oil from entering the intake system, while allowing efficient discharge of oil and reducing the risk of excessive accumulation in the drain pipe.
Implementation Method 1
the valve head portion being moveable in the axial direction of the drain pipe... when a pressure difference between the interior of the oil mist separator and the interior of the engine is small... the check valve is sucked by the intake negative pressure so that the oil discharge hole is closed
Implementation Method 2
when the oil is accumulated in the drain pipe, the check valve is pushed down by a head pressure of the oil so that the oil is drained
Data Source
Figure 1~2
Figure 3~4
Figure 5(A)~5(B)
AI summary
An oil drain structure for an oil mist separator is provided with a check valve (10) that opens and closes an oil discharge hole (8) formed in a lower end portion of a drain pipe (5) of the oil mist separator. The check valve (10) includes: a disc-shaped valve body (11) which opens and closes the oil discharge hole (8) from an outside; a spherical valve head portion (12) fitted in a tubular portion (6) of the drain pipe (5) with a fine clearance (ΔD) between the valve head portion (12) and the tubular portion (6), the fine clearance (ΔD) serving as an orifice; and a rod-shaped stem portion (13) that extends through the oil discharge hole (8) and connects the valve body (11) and the valve head portion (12). When blow-by gas is likely to flow back due to a pressure difference between an intake system and an interior of an engine, the check valve (10) undergoes an upward force due to a pressure difference caused when the gas flows through the fine clearance (ΔD), and the check valve (10) is surely brought into a closed state. When oil is accumulated to a certain height, the check valve (10) descends to discharge the oil.