Flapper Check Valve Stop Surface Design for Wear and Noise
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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.
Innovation Solution
The implementation of conformal contact surfaces and a static stop element with planar surfaces, along with strategically placed bumpers and openings, distributes stress evenly and prevents positional fluctuations, reducing wear and noise, while using a single strip of material for the stop element and mounting posts simplifies manufacturing and reduces weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a narrow stop pin is used to limit rotational movement of flappers, then the open area is maximised, but stress concentration increases leading to wear and reduced operational lifetime
Solution Approach 1:
The patent applies local quality by transitioning from a narrow cylindrical stop pin to a stop element with a broader contact surface. This local structural change distributes the stress over a larger area at the contact point between the flapper and stop element, reducing stress concentration and wear while maintaining the functional requirement of limiting rotational movement.
Solution Approach 2:
The invention moves from a one-dimensional narrow pin contact to a two-dimensional broader contact surface. By expanding the contact geometry from a line contact (cylindrical pin) to a surface contact (stop element with contact surface), the stress is distributed across multiple dimensions, reducing wear and improving reliability.
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 patent applies parameter changes by modifying the material composition of the valve components. It transitions from traditional metallic materials to composite materials or materials with optimized physical properties, maintaining the required strength and durability while reducing the density and overall weight of the moving parts.
3Strength
If metallic materials are used for check valve components, then structural integrity is maintained, but noise during operation increases
Solution Approach 1:
The patent applies composite materials to replace traditional metallic components. These composite materials provide the necessary structural integrity while offering superior damping characteristics that reduce operational noise. The composite structure absorbs vibrations and reduces the noise generated during flapper opening and closing operations.
4Object-generated harmful factors
If elastomeric protrusions are used to cushion contact between flappers and stop pin, then noise is reduced, but fluttering and vibratory movement increase causing wear
Solution Approach 1:
The patent applies local quality by providing a broader contact surface on the stop element that distributes the contact area between the flapper and stop element. This local structural modification reduces stress concentration and prevents the fluttering and vibratory movements that occur with point-contact elastomeric protrusions, thereby improving reliability while maintaining noise reduction.
Data Source
Figure 1A~1B
Figure 1C~2
Figure 3~4
AI summary
A check valve comprising a housing (22) defining a pair of valve openings (24), a pair of flappers (30, 30a, 30b) pivotably mounted to a pin (28) 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 a stop element (42) configured to stop and hold the flappers in the open position. A cavity (50) is formed between the pair of flappers and the stop element when the flappers are in the open position. Each of the flappers comprise one or more contact surfaces (34) configured to contact the stop element when in the open position. The stop element comprises a pair of stop surfaces (44) comprising respective contact areas (44a) configured to oppose and abut the contact surfaces of the flappers when the flappers are in the open position, and said contact area configured to remain stationary. At least one of the contact surfaces of the flappers and contact areas of the stop element are formed on one or more bumpers (32) disposed on a respective one of the flappers and/or stop surfaces. One or more openings (38) are formed between each of the flappers and the stop element adjacent to the one or more bumpers when in the open position. Each of the contact areas of the stop elements are configured to be conformal to the contact surface of a respective flapper when the flappers are in the open position.