Ejector High-Pressure Passage Curvature for Flow Stability
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Solution Overview
Problem
The existing ejector designs for fuel vapor treating devices are sensitive to deformation at the downstream end of the high-pressure passage, which significantly affects the flow velocity and the amount of gas flowing into the low-pressure passage, leading to inconsistent negative pressure generation and gas flow.
Innovation Solution
The design incorporates a high-pressure passage that is bent at one or more locations between the upstream and downstream ends, affecting the flow velocity and negative pressure generation at the connection point, reducing the impact of downstream end deformation on gas flow and ensuring a consistent amount of gas flows from the connection passage to the low-pressure passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the high-pressure passage is straight without bent portions, then the structure is simple and manufacturing is easier, but the flow velocity is significantly affected by deformation at the downstream end, leading to unstable gas flow
Solution Approach 1:
The high-pressure passage is designed with bent portions (curved geometry) instead of a straight configuration. This curvature introduces a stabilizing effect where the bent portions act as flow dampers, reducing the impact of downstream deformations on the overall gas flow characteristics and maintaining more stable flow velocity.
2Reliability
If the high-pressure passage is bent at one or more locations, then the flow velocity becomes less sensitive to downstream deformation and gas flow is stabilized, but the structure becomes more complex
Solution Approach 1:
The bent portions are integrated into the passage design as smooth curves rather than sharp angles or complex geometries. This approach provides flow stabilization while minimizing manufacturing complexity. The curvature radius and bend angles are optimized to achieve the desired flow stability without excessive structural complexity.
3Speed
If the cross-sectional flow area decreases toward the downstream end, then high velocity jet is generated for sufficient negative pressure, but the passage geometry becomes more complex
Solution Approach 1:
The cross-sectional area reduction is applied locally at the downstream end of the high-pressure passage rather than throughout the entire passage. This localized geometry change creates the necessary high-velocity jet for sufficient negative pressure generation while keeping the upstream portion of the passage simple and easy to manufacture.
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 configuration stabilizes the negative pressure generation and gas flow, ensuring a sufficient amount of gas flows from the connection passage to the low-pressure passage, even when the downstream end of the high-pressure passage is deformed, and reduces the overall dimension and manufacturing costs by integrating the ejector portion with the intake housing.
Implementation Method 1
The cross-sectional flow area of the high-pressure passage decreases toward the low-pressure passage. The high-pressure passage ejects high-pressure gas violently from the downstream end to the low-pressure passage. Since the flow velocity of gas in the low-pressure passage is higher than the flow velocity of gas in the high-pressure passage, a negative pressure is generated at the junction of the high-pressure passage and the low-pressure passage
Data Source
AI summary
An ejector includes a high-pressure passage, a low-pressure passage, and a connection passage. The high-pressure passage includes an upstream end and a downstream end. The upstream end is configured to be connected to a passage through which a high-pressure gas flows. The low-pressure passage is connected to the downstream end of the high-pressure passage. The connection passage is connected to a junction of the high-pressure passage and the low-pressure passage. The high-pressure passage is bent at one or more locations between the upstream end and the downstream end.