Nested Spring Assembly for Seal Force and Deflection Balance
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Solution Overview
Problem
Canted coil springs face limitations in seal applications due to limited contact surface area and steep force versus deflection curves, which can lead to uneven force distribution and potential deformation, while helical ribbon springs offer a larger contact surface but with limited deflection capacity and a steep force curve.
Innovation Solution
A spring assembly comprising a helical ribbon spring with an inner canted coil spring or another type of spring that modifies the force versus deflection characteristics, providing additional support and a more even force distribution by having the inner spring contact the interior surfaces of the outer spring's coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a canted coil spring is used as an energizer for a seal element, then the force applied has high magnitude and can recover from large deflections, but the contact surface area is limited to the wire diameter which results in uneven force distribution around the seal circumference
Solution Approach 1:
The patent applies nesting by placing a canted coil spring inside a helical ribbon spring, where the inner spring's coils are contained within the outer spring's coil structure. This nested configuration allows the inner canted coil spring to provide high force magnitude while the outer helical ribbon spring provides a larger contact surface area, resolving the contradiction between force magnitude and contact surface area.
Solution Approach 2:
The patent merges two different spring types (canted coil spring and helical ribbon spring) into a single assembly. The canted coil spring contributes high force magnitude and recovery capability, while the helical ribbon spring contributes larger contact surface area and more uniform force distribution. This combination allows both contradictory requirements to be satisfied simultaneously.
2Area of stationary object
If a helical ribbon spring is used in a seal energizer application, then the contact surface area is greater providing more uniform force against the seal, but the maximum deflection amount before permanent deformation is much lower
Solution Approach 1:
The nested configuration allows the inner canted coil spring to bear the large deflection loads that the outer helical ribbon spring cannot withstand. The outer spring maintains its structural integrity and contact surface area, while the inner spring absorbs the excessive deflection, preventing permanent deformation of the outer spring.
Solution Approach 2:
The inner canted coil spring acts as an intermediary that protects the outer helical ribbon spring from excessive deflection. When large deflections occur, the inner spring engages and limits the deflection transmitted to the outer spring, preventing permanent deformation while allowing the outer spring to maintain its beneficial contact surface area.
3Stability of the object's composition
If a canted coil spring is used, then the force versus deflection relationship is relatively flat maintaining constant load, but the spacing between adjacent coils limits the contact surface area and may cause uneven force distribution
Solution Approach 1:
The patent combines the flat force versus deflection characteristic of the canted coil spring with the continuous contact surface of the helical ribbon spring. The inner canted coil spring maintains constant load through its flat force-deflection curve, while the outer helical ribbon spring provides continuous contact surface area, eliminating the uneven force distribution caused by coil spacing.
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
This configuration enhances the seal performance by maintaining a constant force over a range of deflections, preventing deformation and ensuring a larger contact surface area for even energization of seal elements, thereby extending seal life and improving dynamic operating biasing.
Implementation Method 1
the inner spring is located inside the outer spring, the outer spring is a helical ribbon spring, and the inner spring provides support to the helical ribbon spring... the inner spring comprises an inner cross-sectional profile; wherein said inner cross-sectional profile is located within said outer cross-sectional profile and biased against interior surfaces of the plurality of interconnected coils
Data Source
AI summary
A spring assembly with two or more springs, one inside another. The spring assembly can have two springs wherein one spring is located inside another spring, and the outer spring can be a helical ribbon spring and the inner spring can be a canted coil spring to provide support to the outer helical ribbon spring. Support is provided where the helical ribbon spring may have some limitations that the inner spring is able to overcome. Limitations of the helical ribbon spring may be a limited force versus deflection curve which the additional spring support of the secondary spring may overcome.