Fill Limit Vent Valve Guide Wall Flow Separation
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Solution Overview
Problem
Existing fill limit vent valves increase fuel vapor pressure by restricting fuel vapor flow, hindering liquid fuel entry into the tank while struggling to prevent liquid fuel outflow with the fuel vapor.
Innovation Solution
A fill limit vent valve with a guide wall having inclined guide surfaces between the inlet and discharge port, which changes the flow direction of the air-fuel mixture, increasing resistance to liquid fuel flow while maintaining efficient vapor flow, and includes a second fuel passage to enhance liquid fuel separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the upper wall is added to change the flow direction of fuel vapor to circumferential directions, then liquid fuel outflow is restricted, but fuel vapor pressure increases and liquid fuel entry is hindered
Solution Approach 1:
The fuel passage is divided into two separate passages: a first fuel passage for liquid fuel and a second fuel passage for fuel vapor. This segmentation allows each passage to be optimized for its specific function, with the vapor passage designed to minimize resistance and the liquid fuel passage equipped with separation structures to prevent outflow.
Solution Approach 2:
A separator is introduced as an intermediary component between the two fuel passages. The separator prevents liquid fuel from entering the vapor passage while allowing vapor to pass through, thereby eliminating the harmful effect of liquid fuel outflow without increasing vapor pressure.
2Object-generated harmful factors
If the flow direction is changed from vertical to orthogonal direction, then liquid fuel separation is enhanced, but flow resistance increases and vapor pressure rises
Solution Approach 1:
The fuel passage is divided into two separate passages: a first fuel passage for liquid fuel and a second fuel passage for fuel vapor. This segmentation allows each passage to be optimized for its specific function, with the vapor passage designed to minimize resistance and the liquid fuel passage equipped with separation structures to prevent outflow.
Solution Approach 2:
Different structural features are applied to different parts of the system: the second fuel passage has a smooth, resistance-minimizing structure for efficient vapor flow, while the first fuel passage has separation structures like float valves and check valves to prevent liquid fuel outflow. Each local structure is optimized for its specific function.
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 restricts outflow of liquid fuel and limits fuel vapor pressure increase, ensuring efficient separation of liquid fuel from vapor and maintaining ease of refueling by gradually changing the flow direction and extending the fuel passage.
Implementation Method 1
A guide wall that has at least one guide surface is provided between the inlet and the discharge port of the fuel passage. The guide surface is configured to change a direction of flow of the liquid fuel and the fuel vapor. A straight line on the curved surface that is parallel with the central axis is defined as a generatrix. The guide surface extends along the curved surface while being inclined relative to the generatrix.
Implementation Method 2
the float valve moves upward as the level of the liquid fuel flowing into the tubular portion via the fuel passage rises, and closes the communicating opening, so that the flow of fuel vapor to the outside of the housing is shut off
Implementation Method 3
A guide wall that has at least one guide surface is provided between the inlet and the discharge port of the fuel passage. The guide surface is configured to change a direction of flow of the liquid fuel and the fuel vapor. A straight line on the curved surface that is parallel with the central axis is defined as a generatrix. The guide surface extends along the curved surface while being inclined relative to the generatrix.
Data Source
AI summary
A fill limit vent valve includes a float valve, a housing, and a lid. The housing includes a cylindrical outer wall and a tubular portion. The outer wall has a central axis. The tubular portion accommodates the float valve. The lid is placed on the upper end of the tubular portion and has a communicating opening. The housing includes a fuel passage that has an inlet and a discharge port. The discharge port is connected to the communicating opening. A section of the tubular portion that faces the fuel passage is constituted by a curved surface. A guide wall that has at least one guide surface is provided between the fuel passage and the inlet. A straight line on the curved surface that is parallel with the central axis is defined as a generatrix. The guide surface extends along the curved surface while being inclined relative to the generatrix.