Hydrodynamic Seal Assembly with Precision Clamping Control
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Solution Overview
Problem
Hydrodynamic seals in aircraft applications face challenges with sealing surface distortion due to insufficient precision guidance from clamping nut threads, leading to variations in coning values and reduced sealing reliability, especially with extended maintenance service intervals.
Innovation Solution
Incorporating a spring component with a clamping nut, a clamping surface parallel to the thread pitch, and a pilot surface to provide uniform clamping force and control coning, thereby minimizing distortion and ensuring precise load distribution around the mating ring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a clamping nut with threads is used to secure the mating ring, then the mating ring can be attached to the shaft, but the threads do not provide sufficient precision guidance causing sealing surface distortion
Solution Approach 1:
A precision guide surface is introduced as an intermediary element between the clamping nut and mating ring. This guide surface provides the necessary precision guidance for the clamping load application, while the clamping nut continues to provide the securing function. The guide surface acts as a mediator that transfers the clamping force with proper alignment, preventing sealing surface distortion.
Solution Approach 2:
The clamping nut assembly is segmented into distinct functional elements: the clamping nut itself for applying load, and a separate precision guide surface for providing alignment guidance. This segmentation allows each element to optimize its specific function - the nut for clamping and the guide surface for precision positioning - thereby resolving the contradiction between securing capability and precision control.
2Ease of manufacture
If standard tolerancing is used for interface control surfaces, then manufacturing is simplified, but sealing surface distortion occurs due to insufficient precision guidance
Solution Approach 1:
A dedicated precision guide surface serves as an intermediary that concentrates the precision requirement to a specific location rather than requiring all interface control surfaces to high precision. This allows other interface surfaces to use standard tolerancing for ease of manufacture, while the guide surface provides the necessary precision guidance for sealing surface control.
3Adaptability or versatility
If coning values are varied to accommodate thread variations, then assembly flexibility is improved, but sealing reliability decreases due to insufficient precision guidance
Solution Approach 1:
The precision guide surface acts as a stabilizing intermediary that maintains consistent coning values regardless of thread variations. By providing a fixed, precise reference surface, it decouples the relationship between thread variations and coning values, allowing assembly flexibility while maintaining sealing reliability through consistent geometric control.
Data Source
AI summary
A hydrodynamic seal (10) for use with a rotating shaft (24) is disclosed. The seal includes a face seal (20) and a mating ring (22) fixed or connected to rotate with the shaft. A clamping nut (30) is adjacent to the mating ring and includes threads to secure a portion of the clamping nut to the shaft via a threaded interface (32). Embodiments of the seal and related assembly include at least one of: a spring component (140) with or on the clamping nut; a clamping surface (150) on an interface between the mating ring and the clamping nut, the clamping surface being substantially parallel to a thread pitch on the threaded interface; and a pilot surface (250) on the clamping nut.