Check Valve Stop Pin with Flexible Tongues for Impact Damping
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Solution Overview
Problem
Check valves in aircraft air conditioning systems experience high stresses due to the impact of flappers on stop pins, which can lead to premature wear and failure, despite existing damping arrangements.
Innovation Solution
The introduction of flexible cantilevered tongues attached to the stop pin, which absorb the impact of the flappers by flexing inwardly, reducing stress concentrations and improving the damping effect, and the use of L-shaped slots with rounded ends on the stop pin to enhance this damping mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a stop pin is provided to limit the rotational movement of flapper elements, then the flappers can be stopped at a predetermined position, but high stresses occur in the flappers or stop pin due to impact force
Solution Approach 1:
The patent changes the physical state and mechanical properties of the stop pin by incorporating flexible tongues with varying degrees of flexibility. The tongues are designed with different flexibilities to absorb impact forces through elastic deformation, transforming the rigid stop pin into a compliant structure that reduces stress concentrations while maintaining the stopping function.
Solution Approach 2:
The stop pin is constructed as a composite structure combining a rigid pin body with flexible tongue elements. This composite design allows the rigid portion to provide structural support and positioning, while the flexible tongues absorb impact energy through deformation, reducing overall stress on the assembly and extending service life.
2Stress or pressure
If damping arrangements are provided between the stop pin and flappers, then impact stresses are reduced, but the device complexity increases
Solution Approach 1:
The patent merges the damping function with the stop pin structure itself by integrating flexible tongues directly into the pin body. This eliminates the need for separate damping components or arrangements, reducing device complexity while maintaining the stress-reducing damping effect. The stop pin simultaneously provides both the stopping function and the damping function through its integrated flexible tongue design.
3Reliability
If multiple slots and tongues are provided on the stop pin, then the damping effect is enhanced, but the manufacturing precision requirements increase
Solution Approach 1:
The stop pin is segmented into multiple slots and tongues, dividing the damping function across several elements. This segmentation distributes the impact forces across multiple flexible tongues, enhancing the overall damping effect and reliability. The modular segmented structure also provides redundancy, where individual tongues can deform independently to absorb energy.
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
The proposed solution effectively mitigates the impact stresses on both the stop pin and flappers, potentially extending their lifespan and improving the overall reliability of the check valve by varying the point of impact and size of the tongues.
Implementation Method 1
The stop pin comprises a number of slots therein defining flexible, cantilevered tongues. The slots are arranged such that, in use, the flappers contact the tongues and cause the tongues to flex inwardly towards one another.
Data Source
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AI summary
A stop pin (18) for a check valve (2), the stop pin (18) comprising a first end (64A) and a second end (64B) and extending from the first end (64A) to the second end (64B) in a longitudinal direction along a longitudinal axis; the stop pin (18) comprising at least one slot (52A, 52B) therein extending in said longitudinal direction, said at least one slot (52A, 52B) defining a respective at least one flexible, cantilevered tongue (54A, 52B) having a free end (58) and a connected end (60) connected to said stop pin (18).