Flapper Check Valve Stop Geometry for Wear and Noise Reduction
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Solution Overview
Problem
Conventional check valves used in aerospace, such as aircraft check valves, experience wear and noise issues due to high stress concentrations at narrow contact areas between flappers and stop pins, leading to reduced operational lifetime and increased weight from metallic materials.
Innovation Solution
A check valve design featuring conformal contact surfaces and bumpers on flappers and stop elements with large contact areas, along with a static, non-resilient stop element, to distribute stress evenly and prevent fluttering, while using a lightweight, flat strip of material for the stop element and mounting posts to reduce weight and manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a narrow stop pin is used to limit flapper rotation, then the open area is maximized, but stress concentration increases causing wear and reduced operational lifetime
Solution Approach 1:
The stop element is segmented into multiple contact points distributed along the flapper surface, transforming a single narrow contact into multiple wider contact zones. This segmentation increases the total contact area, reducing stress concentration while maintaining the flapper's rotation limit function.
Solution Approach 2:
The stop element extends in a dimension parallel to the flapper surface rather than perpendicular to it. This dimensional change allows the stop element to contact the flapper along a line or area rather than at a single point, increasing contact area without interfering with the flapper's rotational movement or reducing the open area.
2Strength
If metallic materials are used for flapper and stop pin components, then strength and durability are improved, but weight increases undesirably
Solution Approach 1:
The invention employs composite construction where the stop element is made from a material with different properties than the flapper. The stop element uses a lightweight non-metallic material (such as polymer or composite) that provides sufficient strength for its stopping function while significantly reducing weight compared to traditional metallic components.
3Strength
If metallic components are used in check valve, then structural strength is maintained, but noise production increases during operation
Solution Approach 1:
The invention changes the material parameter of the stop element from metallic to non-metallic (polymer or composite material). This material parameter change reduces noise generation during flapper contact while maintaining sufficient mechanical strength for the stopping function, and also reduces weight.
4Object-generated harmful factors
If elastomeric protrusions are used to cushion contact between flappers and stop pin, then noise is reduced, but fluttering is not prevented and wear on hinge pin increases
Solution Approach 1:
Instead of using compliant elastomeric material on the stop pin, the invention inverts the approach by using a rigid or semi-rigid stop element with a specific geometric shape that naturally distributes contact pressure. The stop element's shape is designed to contact the flapper in a way that prevents concentration of forces that would cause hinge pin wear, while still reducing noise through the material selection.
Data Source
AI summary
A check valve includes a housing defining a pair of valve openings, a pair of flappers pivotably mounted to a pin and such that they are configured to rotate relative to the housing between an open position in which they permit fluid flow through the valve openings and a closed position in which they prevent fluid flow through the valve openings, and an element configured to stop and hold the flappers in the open position. A cavity is formed between the pair of flappers and stop element when the flappers are in the open position. Each of the flappers comprise one or more contact surfaces configured to contact the stop element when in the open position. The stop element has stop surfaces with stationary contact areas configured to oppose and abut the flapper contact surfaces when the flappers are in the open position.