Conical Metallic Ring Seal for Abrasive Rotary Interfaces
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Solution Overview
Problem
Existing sealing technologies for rotary actuators in space-based applications, particularly in environments with abrasive media like soil or dust, fail due to ingress of particles and thermal expansion issues.
Innovation Solution
A shielding apparatus featuring a preloaded, conically shaped metallic ring made of stainless steel, dry film lubricated, installed between the rotary and stationary housings of the actuator to prevent abrasive media ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a combination of energized polymer seal and cloth wiper with labyrinth path is used to seal the rotary actuator, then sealing effectiveness is improved, but the seal fails under thermal extremes and abrasive media due to CTE differences and material degradation
Solution Approach 1:
The patent changes the material parameter from polymer/cloth to metallic material, which maintains its mechanical properties and dimensional stability under thermal extremes. The metallic seal ring undergoes predictable thermal expansion that can be accommodated by the conical geometry and preload mechanism, preventing seal failure due to CTE differences.
Solution Approach 2:
The patent employs a composite structure combining metallic seal ring with dry film lubricant coating. This composite approach provides both the thermal stability of metal and the low-friction surface properties of the lubricant, creating a seal system that withstands both thermal extremes and abrasive media.
2Reliability
If a combination of energized polymer seal and cloth wiper with labyrinth path is used to seal the rotary actuator, then sealing effectiveness is improved, but the seal fails under abrasive media due to material degradation
Solution Approach 1:
The patent changes the material parameter from soft polymer/cloth to hard metallic material, which resists degradation from abrasive media. The metallic seal ring maintains its structural integrity and sealing capability even when exposed to soil particles and dust, preventing the material degradation that plagues polymer-based seals.
Solution Approach 2:
The patent employs a simple metallic ring design that can be easily replaced if worn, rather than relying on complex multi-component seals that degrade. The simplicity of the metallic seal allows for straightforward maintenance and replacement in harsh space environments.
3Reliability
If a flat metallic ring is preloaded into a conical shape between rotary and stationary housings, then prevention of abrasive media ingress is achieved, but rotary drag increases due to contact pressure
Solution Approach 1:
The patent employs a conical geometry for the metallic seal ring instead of a flat configuration. This curvature allows the seal to deflect and conform to the mating surfaces while maintaining a smaller contact area, reducing friction and rotary drag compared to a flat seal under the same preload conditions.
Solution Approach 2:
The patent uses a thin metallic ring that can flex and deform elastically under preload to achieve conformal contact with the housing surfaces. This flexibility allows the seal to maintain effective sealing without requiring excessive contact pressure, thereby minimizing rotary drag.
4Loss of energy
If dry film lubricant is applied on all sliding surfaces of the metallic ring, then reduction of rotary drag is achieved, but lubricant degradation under thermal extremes may occur
Solution Approach 1:
The patent employs a thin dry film lubricant coating that can be reapplied if degraded, rather than relying on permanent lubrication. The dry film provides initial low-friction operation but is designed to be replaceable, ensuring long-term reliability even if the lubricant degrades under thermal extremes.
Solution Approach 2:
The patent uses dry film lubricant instead of liquid or grease-based lubricants, which have better thermal stability. The dry film coating maintains its lubricating properties across a wider temperature range and does not degrade as rapidly under thermal extremes, though it may still require periodic replenishment.
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 metallic ring effectively prevents the ingress of abrasive media while minimizing rotary drag, maintaining contact with the housings during rotation, and being less sensitive to temperature changes compared to non-metallic seals.
Implementation Method 1
The flat metallic ring is preloaded into a conical shape when installed between the rotary housing and the stationary housing
Implementation Method 2
The metallic ring is dry film lubricated by applying a dry film lubricant on all sliding surfaces of the metallic ring
Data Source
AI summary
An apparatus for shielding a rotary interface to prevent ingress of abrasive media is provided. The apparatus includes a flat metallic ring that is installed between a rotary housing containing a rotating component and a stationary housing containing a stationary component configured to interface with the rotating component to provide rotational motion. The rotary housing is configured to couple to the stationary housing and rotate with respect to the stationary housing when coupled. The flat metallic ring is preloaded into a conical shape when installed between the rotary housing and the stationary housing.