Flow Control Valve Geometry for Smooth Fuel Tank Depressurization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional shut-off valves in evaporated fuel processing devices for vehicles experience issues with rapid fuel flow during refueling, leading to dynamic pressure in the vapor conduit and potential float valve closure, which disrupts smooth depressurization of the fuel tank.
Innovation Solution
A flow control valve with a housing, valve seat, electric motor, and valve body featuring a straight projecting portion that restricts fluid flow in the initial lifting range, preventing excessive flow rate increase and maintaining controlled fluid flow through a fluid-flow channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the valve body is quickly opened to reduce tank inner pressure before refueling, then the depressurization speed is improved, but the fluid flow rate increases rapidly causing dynamic pressure buildup and potential float valve closure
Solution Approach 1:
The valve body incorporates a straight projecting portion that dynamically adjusts the flow passage area during the opening process. In the initial opening stage, the projecting portion restricts the flow area to control flow rate and prevent dynamic pressure. As the valve opens further, the projecting portion moves away from the valve seat, allowing the flow area to increase and flow rate to rise, achieving rapid depressurization without harmful pressure buildup.
Solution Approach 2:
The straight projecting portion changes the flow characteristics by modifying the effective flow passage area as a function of valve opening distance. This geometric feature creates a controlled parameter transition where the flow area initially increases slowly (restricting flow rate) and then increases more rapidly (allowing high flow rate for fast depressurization), resolving the contradiction between depressurization speed and dynamic pressure control.
2Productivity
If the valve body lifting distance is increased to increase flow rate, then the fluid flow control is improved, but the flow rate increases too rapidly in the initial lifting range
Solution Approach 1:
The straight projecting portion creates a dynamic flow control characteristic where the relationship between valve lifting distance and flow rate is non-linear. During initial lifting (0 to 2mm), the projecting portion maintains a restricted flow area, preventing excessive flow rate increase. During later lifting (2mm to 10mm), the flow area increases more rapidly, enabling high flow rate for efficient depressurization. This dynamic control resolves the contradiction between flow control capability and preventing excessive flow rate.
Data Source
AI summary
A flow control valve may include a housing including a fluid-flow channel, a valve seat including a valve hole and positioned in the fluid-flow channel, an electric motor disposed in the housing, and a valve body configured to be axially moved toward and away from the valve seat by the electric motor via a feed screw mechanism. The valve body includes a straight projecting portion. The projecting portion is configured to be positioned in the valve hole in an initial valve body lifting range in which a lift distance of the valve body relative to the valve seat is not greater than a predetermined lift distance.